I am still suffering after twenty years of ignoring my IBS symptoms. Here are my recommendations: Avoid Nightshades as they are irritants - they may not be what you are having a reaction to however they should be avoided while you heal your gut. (all tomatoes, all potatoes except sweet potatoes, eggplant, bell peppers, and red spices such as paprika, cayenne, red pepper and chili pepper). Remove gluten and as much sugar as possible. Gluten is a very common irritant and if you have bloating and gas I bet it is a cause. Look up the Paleo Diet - there are several books out now by nutritionists that offer information and recipes to handle healing the gut. Sugar is a poison - and it is in almost every processed food - shop the perimeter of the gorcery store for healing your gut. Coffee and Chocolate are also irritants as well as alcohol. So, in other words to truly heal your gut stick to simple meat and veg and fruit, sea salt, black pepper and garlic to season, you can have quinoa and sweet potatoes for starch. Introduce a great probiotic - with 6-7 strains with a 10 billion or greater count. Find other healing probiotics at health food stores - kombucha, kefir (in coconut water) and make your own fermented food. You can make your own pickles and kraut with sea salt and water (no vinegar). Within a couple of days you have great healthy probiotic that you grew in your own kitchen! After about
30 days you can reintroduce stuff (tomatoes, potatoes, etc if you would like).
I myself have been on a paleo journey for a while and only recently determined that nightshades are irritating me. It's all trial and error. elimination training is the best course if you have ruled out other diseases. You are what you eat