I used to have major IBS problems along with serious allergy issues. Going on a paleo style diet relieved those two issues about 90%. I also used to eat a lot of whole wheat bread and cereals. Removing those from my diet was the key to eliminating my IBS and allergies. Gluten is a serious concern to people with gut issues since they destroy the micro villi in your small intestine. Without your small intestine working properly you won't be absorbing key nutrients. It was a long process of eating gluten/grain free and removing dairy products. I made a lot of bone broth early on. Cruciferous vegetables tend to give a lot of people gas and discomfort. But I do pretty well with most vegetables. For me the main perpetrator was grains and gluten especially. You may want to look into that if you can.
"If man made it, don't eat it" - Jack Lallane
People say I am on a "crazy" diet. What is so crazy about eating veggies, fruits, seafood and organ meats? Just because I don't eat whole wheat and processed food doesn't make my diet "crazy". Maybe everyone else with a SAD are the "crazy" ones for putting that junk in their system.