Feeling really awful about myself and my son.

Hiya @Hope54321 ,
I know a few pp suggested trimethylaminuria and you said you haven't tested for it but it could be that.
It is genetic and it can cause horrendous breath problems.
You really have to restrict your diet in order to get a bit of relief and to take antibiotics every few months to kill off the bacteria that is causing it.
You seem to have exhausted all other options and you have fastidious dental hygiene.
There are many sufferers in the UK who know exactly what you are experiencing. Sending hugs x

Have you tried Diatomaceous earth?

Try the probiotic bacillus salivarius - 2 a day on an empty stomach and Retardex mouthwash. Absolute game changer for me

Endoscopy to rule out intestinal leakage?

That's terrible advice, meat makes you stink. It makes your body odour and feces smell stronger, it makes you sweat more, it makes your sexual secretions stink, and most importantly, the cysteine in protein feeds bacteria in the mouth.

I was going to say STOP eating meat and fish!

But, you only say you scrape your tongue - that doesn't clean it at all. Plus you say it gets worse when eating sugar. This implies the problem is bacterial.

You should clean your entire tongue with toothpaste and toothbrush, all the way back to the epiglottis. Doing this, I never even get morning breath. Sometimes I need to do it twice, and I also need to "rinse" the tongue after by cleaning it with only water on my toothbrush.

I get tonsil stones, and I can tell when the tiniest fragment of food or particle is caught in there. It does smell like it's coming from deeper within, rather than the mouth itself. This is because you smell the gases they give off, which seem to be emanating from within you, but they're not.

You say they checked, but they wouldn't be able to see small tonsil stones or tiny food particles. Just get a water pick, put it on the lowest setting, and thoroughly clean your tonsils and see what comes out.

My dad's breath had that manure smell. My tonsil stones smell exactly like that, so I took action immediately. With a clean tongue and tonsils my breath is always perfect, except post-garlic.

Are you breast feeding a 4 year old? Maybe you’re passing on whatever is causing your bad breath to him and his will improve if you stop?!

My daughter had bad breath. The doctor prescribed pepto, which we thought was going to be a waste of time as she doesn’t have any acid reflux. Turns out it worked!! You can buy it over the counter, nothing to loose if you haven’t tried it.

If the smell becomes significantly worse during colds, then it could be a sinus-related drainage issue (including adenoids in children), possibly made worse by reflux. This would fit why it affects your son as well, because nasal/sinus shape is inherited.

Your sinus anatomy or enlarged adenoids could be causing it (See ENT to diagnose)

Stagnant mucus smells faecal.

You could try a daily saline nasal care to remove old infected mucus before it can smell.

You could ask your GP for a nasal steroid spray (fluticasone, mometasone) to reduce swelling and improve drainage.

Steaming to prevent mucus from thickening and rotting, and drinking lots of water, would also help if it is the mucus.

Even mild silent reflux increases inflammation in the nose and throat, so take steps to avoid reflux, like not lying down after food, avoiding trigger foods etc.

Oil pulling isn't part of Dr Ellie's system, there are 3 mouthwashes along with xylitol aimed at feeding the good bacteria and killing the bad bacteria that will cause bad breath.

Xylitol mints are much better than gum so you don't chew for too long. Chewing xylitol for a few minutes produces the mineral rich saliva that you need, chewing for longer creates digestive saliva. So chewing xylitol gum for too long won't help at all. It's best to consume xylitol after every drink or meal

Listerine original will help with killing the bad bacteria.

https://www.medicalnewstoday.com/articles/metabolic-disorders-that-cause-bad-breath#treatment

Do you think the smell comes from your breath (as in the air you are breathing out) or your mouth? Most bad breath is caused in the mouth, but less commonly its the smell of something being excreted in the breath itself. You could try to tackle one until you're blue in the face if the root cause is the other.

Op. Omezarapole won't do much for LPR no, it's a vert strict diet and if your persist with it it does help. There's also a surgical option.

I too have the chronic bad breath, it can be smelt from meters away, I won't even get taxis anymore after a driver opened his window because of the smell.....mine is up and down with management but when I stick to it the smell does go, itsl flared up at the mo because I stupidly ate a piece of Christmas cake 🙄. It's a miserable way to eat but it's worth it.

Not surprised. No-one w reflux should be drinking apple cider vinegar.
So you do have reflux? And it can be hereditary- most of my family suffer to some degree - me, dh, ds and my BIL and his DC.
Have you had an endoscopy?

This is interesting.

https://www.radboudumc.nl/en/news/2017/gene-mutation-causes-chronic-bad-breath

The SELENBP1 mutation is rare but not super-rare (1 in 80,000). It is more likely to be genetic given that your son had it from birth. There may be a urine test mentioned here: https://omim.org/entry/618148

Has anybody discussed pku with you. It is very rare but worth some research.

Consider looking at hair mineral analysis and taking the recommended vitamins/minerals to rebalance any deficiencies or excess. My husband had bad breath when we first got together but on part of the infertility journey we tried this and I believe it cured his bad breath.

I read that bad breath can be a sign of kidney disease. I hope you both manage to solve the mystery. It sounds miserable.

Sounds like you have explored so many routes and have the basic and obvious routines very much in place.

Has there been any time in your life when the breath has been better?

There must be specialist doctors or scientists who can help throw some light on this. I would try looking into who is writing research papers on the topic and try to make contact with them.

I’d probably have my tonsils removed just to completely 100% rule it out

Tonsils removed?