Creatine is extremely well researched, well understood, and above all, very safe. I've been taking it for years even during flares. I've even read reports of it being used in hospitals for bedridden patients to combat muscle atrophy. I do suggest drinking at least a gallon of water a day (everyone should do this anyway) because if you are dehydrated from diarrhea then taking creatine could potentially be harmful. The same can be said for almost any OTC drug, prescription, or supplement though. I suggest you save your money, get plain micronized creatine monohydrate powder. Lots of various formulations exist that claim to improve absorption, cell saturation, whatever. The research shows that they are wrong. Period.
As far as aminos go, I assume you mean BCAA's? I don't have much experience with them but I do know citruline malate often causes some gastrointestinal side effects. So be careful and actually read the label before you buy anything.