Hello, sorry I do not know much about your condition. Whey isolate and even better but more expensive is hydrolyzed whey are very easy to digest and assimilate in the body. Hydrolyzed is very good and has the highest absorption of any protein I know of. This may help.

Legumes are good for you but do not count on these being a large part of your daily protein intake. The proteins in legumes takes a much higher rate of consumption to equal the same amount amount of total beneficial aminos to build muscle. They just are not even close as good as chicken, fish and eggs for muscle building but are great for gut health and fiber. Don't stop eating them, just count your prateins from you meat. (Again, eggs are a great source which is easily digested and a complete protein which most beans are not)

As for creatine, go 5-6 grams.
BCAA's may help with your problem too. I just take a whey isolate and hydrolyzed whey supp after training. it contains all of the BCAAs as well as all the other essential and non essential aminos. BCAAs may benefit you are well with the mal-absorption.

Hope this helps.