Re: why am i having diarrhea every time i eat
yes gallbladder can affect fat digestion. This causes problems during digestion, and when the food reaches the large intestine it will cause water to move into the large intestine and therefor cause diarrhea. As the composition of what comes out is fat, a way to check this is for floating...yea.
Coeliac disease is an autoimmune response due to the immune system recognising GLUTEN as foreign material and triggers an immune response. This will cause inflammation of the small intestine and will lower the small intestine's ability to absorb of foods. Same thing happens when the food reaches the large intestine. High conc of what ever you have will cause water to move out of the body -> so diarrhea.
Both are very valid possibilities. It just comes down to what you have eaten.
My suggestion is that you try a gluten free diet and see if there is any change.
Im not too sure on the onset of coeliac disease as it is very hard to diagnose. But gallbladder issues normally arise from gall stones or infections, which is often painfull