Since I have IBS, almost any food can bother me. And one day it will bother me and the next day it won’t. It’s totally goofy. I went gluten free and that didn’t help (as in it didn’t take away my main issues). I went lactose free and a reduction in dairy definitely helps when my stomach is upset but it didn’t take away my issues. I’ve done lactose and gluten free. It simply made no big impact in my life but everyone is different and fibro presents itself differently in everyone too so it’s hard to say what works for one person will work for another. Things that bother me the most are healthy things like fruit and salad because of the IBS, so none of it makes a lot of sense. I eat what sounds good and go from there.

We are very sensitive to everything.
I went with out wheat, sugar, gluten, soy, dairy, and
MSG for years. It didn’t help anything accept my bloating.
Now I avoid sugars, soy and MSG. For me MSG is the worst. And it’s in many products like ranch dressing, Dorretos, even chick filet chicken.
You should try avoiding one thing for a week then put it back in your diet and see how you react to it.
Good luck.

Unfortunately have many allergies to foods, environment and dogs and cats. Have anaphylactic reactions to strawberries, pork roast, papaya, mango, and sensitivity to white flour which is in most baked goods. Milk also gives me issues so lactaid is used daily. Love yogurt and cottage cheese but sometimes eating them is just not worth it. I have IBS also among my other ailments. Can eat chicken or Turkey everyday with no problem but beef no more than twice a week with several days between, love kielbasa, smoked sausage, bratwurst and fried bologna but it's a constant balancing act. Is the abdominal pain and possibility of loose stools worth it? Sometimes yes, other times no. Enough of this.

Gluten for sure

What MelodieMalone said! Lactose for sure, but other than that, it depends on the day. If I keep the processed foods out, I see an improvement. Probiotics and enzyme replacement are essential for me now, body just can't process food without them. I have found that a couple of slippery elm capsules to coat the stomach about twenty minutes before eating really helps. Just have to be careful with the timing because it can interfere with medication absorption if taken too close together with meds.