Feeling really awful about myself and my son.

Have you asked for a referral to an ENT specialist?
This doesn't sound like something within the GPs scope of knowledge.

I'll probably get told off on here, but I would see a naturopath or homeopath for this.

Op try fermented products for your gut. I reckon that’s the issue.

Op, has the doctor confirmed that they feel both you and your son have bad breath?

Maybe SIBO, OP? Do you have any other symptoms?

LPR is notorious for causing bad breath.....I have it too and it's horrific.

It sounds like you have that too.....or GERD. Don't be adding acidic anything to your diet, you need to have an extremely low acid diet. No spices, no garlic, no onion etc, low fat and little red meat. . It's miserable but if you stick to it you do get results. There are groups on Facebook for people who have Gerd and lpr which are really helpful.

Can you try something sweet to disguise your breath? Like a sugary snack? I know that's like the opposite of sense but 🤷‍♀️🥺

Sorry girl, its not nice to see your baby suffering xx

Endo like PP mentioned will sort this but obviously not the easiest of tasks

Sorry OP, this sounds awful.
I would cast the net wider and post on more international forums like Reddit/ Askdocs and WebMD. These do get medical experts replying and many like trying to find a mystery diagnosis. You will of course have to weed out the unqualified rubbish but maybe worth a try.

It’s interesting that you said your breath smells like poo. Have you had any scopes (with a camera) to see if there was a connection (or misconnection) from your intestines to your stomach? The GI system can give off all kinds of nasty smells.

Another possibility is systemic candida. This can cause bad breath.

How difficult for you, OP.
No advice other than keep pushing with your doctor. Say how badly it affects your life AND your son's life.
There will be a medical explanation for this so do persist.

I used to post on Natural Mamas forum and someone on there had a baby who started to smell awful- turned out the baby had shoved a pea into its nose and it just stayed there in the sinus cavity, or something. Could there be something in your sinuses or ear canals (as ears, nose, and throat are all linked)? Suggesting as it seems you have tried everything, so maybe it’s time to consider the very very unlikely?

Could you have tonsillitis stones, they can be hard to see on yourself and often cause horrific bad breath, my mum had this until she had her tonsils removed and now has nice fresh breath instead of the death breath (it literally smelled like decomp) she had.

So you have a good hygiene routine and you mind what you eat so it's obviously something medical. I would keep seeing specialists ; gut, orl etc

This is great advice.

Research food-grade diatomaceous earth - drink with lots of water and swirl it around your mouth too

Use a good probiotic (you will need to do this for several months to see proper results) but it will definitely help. Bad breath usually comes from the gut. Treating acid reflux is not getting to the root cause

and a good digestive enzyme as PP says

Age appropriate probiotics and digestive enzymes will help your son's skin issues too

Best of luck

Are you sure it's acid reflux? Have you seen an ENT? I would want a better answer because it sounds unpleasant, I struggle with tonsil stones (and finally got a referral for a tonsillectomy but then mislaid it for a year and probably have to get it renewed )

I am a bit sceptical of the whole "companies that will test your biome and suggest a list of supplements which they conveniently stock at £££££££ prices" business model TBH but even so - I have come across one which does it for the oral biome which I was considering. They did an AMA on reddit: https://www.reddit.com/r/IAmA/comments/sutduc/were_the_founders_of_an_oral_microbiome_testing/

How are your gums? Are they inflamed and prone to infection or are they firm and healthy? I tend to get chronic gum inflammation and my mouth seems to produce a massive amount of plaque at all times, even when I cut down on sugar. My assumption is that there is something out of whack with the biome and this is somehow causing a cyclical effect so the extra bacteria from the plague and the bits of food which get trapped by the inflamed gums feed the tonsil stones and then the tonsil stones hang around and sort of act as a source of further bacteria to irritate the rest of my mouth. I used to be terrible with dental hygiene and I assumed it was due to this for years but then I got into much better habits with it and even when I keep up the good habits I still have the same cycle going on. It's better managed the more I keep up with brushing/flossing but it never fully goes away and I think I get symptoms of Oral Lichen Planus, which I intend to discuss with my dentist on my next visit.

The dentist was interested in my tonsil-gum link theory because she'd never come across a link between the two in literature and technically they are totally different areas of medicine, which could be why apparently. It seems logical that they could affect each other, since they are physically so close together.