@Atomicblondiee
Regarding the OP husband, I couldn't see any mention of him being unhealthy or ill, just bad smelling farts, it's not the end of the world. We all fart and they never smell good!
She said he's been told he has IBS. She has expanded further on his diet when asked and many of the things she said they eat regularly would be triggers for most IBS sufferers.
And I don't think the below description is anywhere close to 'normal' smell levels. OP says she can't rid the house of the smell. The poor bloke must feel constantly on edge and humiliated by his body's issue. His social anxiety caused by this issue is also likely to be another trigger.
I know it sounds like im exaggerating but the smell is so putrid its enough to clear a room, utterly foul smelling, and happens regularly throughout the day, he works from home luckily (or unlucky for me!) although doubt work could sack someone for farting anyway. I dont go in his home office as it stinks. In summer at least we could open windows in the house!
He is very self conscious and he worries that when we're out socially that people are put off, if he tries to hold it in he gets bad gas pain. We were at my sisters a few weeks ago for dinner and her kid ended up getting blamed for the stink, we were both too embarrassed to say anything, and now hes saying he's not going again.
His current diet is not working for his body. That's not an anti-vegan statement, it's a fact.
Instead of being open to people's suggestions of him trying different foods (these could still be vegan) or reducing certain foods he currently eats, OP just keeps repeating that he's healthier than ever and that he would never eat meat, even though she earlier said she had looked in the bins for evidence he might be.
But he's not healthier than ever. Because he is passing gas so foul smelling she often can't tolerate sharing a room with him, their home constantly smells and the poor fella now has social anxiety which is affecting their life together. I feel so sorry for him, his mental health must be being so damaged from the effects of this issue.
He needs to take control and get this looked into more, privately if needed, but he will be asked to FODMAP properly and OP should be supportive of this rather than keep saying that it can't be the diet that's the issue as she eats the same thing and she's fine...
I'm not allergic to cherries but my partner is. If he ate some and had an allergic reaction, i can't imagine saying well I'm fine when I eat them so it can't be that he's got an issue with.