My 28 month boy has in last 6 days started passing excessive/xplosive gas with quite a bit of mucus. stools seem normal when they happen.

Intolerance: He has developed an aquire Mal - digestion problem. Most of the time this is difficulty digesting sugars in the riet. He may have had a little GI bug, and lost the ability to digest those dietary sugars like lactose, sucrose and fructose. Go to a high protein, low fiber diet with complex carbohydrates, avoiding juices, dairy, and simple sugars. Add in a probiotic daily as well.