Try the clear sodas that have no carmel color or azo dyes, real sugar instead of HFCS. I think they are in WalMart. Better yet, avoid sodas. They contribute too much to bloating gas. Sodas give me gas immediately.
For milk if you seem sensitive, try lactose-free milk. Avoid ice cream, cheese, and yogurt while you are testing milk. There are a couple of proteins in milk that can cause problems too. Lactose gives me gas in about
half an hour.
Stick with a rice cereal like Special K. Oatmeal or cream of rice is even less likely to cause problems. Use honey or cane sugar, no brown sugar! Rice doesn't cause gas, but all the sweeteners do! Sugar too! Stevia too - from the dextrose used as filler. Oats have a lot of soluble fiber, which causes gas. Dry cereal gives me gas in half an hour to an hour.
You can try avoiding bread for a while too. A lot of people develop sensitivity or allergy to wheat over their lifetime.
Drop one thing at a time to see which ones are really the culprits. Keep a food journal!