Mel, a lot of what you're going through could be due to the long-gone gallbladder. Are you following a low-fat diet? Losing the GB can sometimes result in ill-timed release of bile into the intestinal tract, and that, in turn, can cause loose stools or true diarrhea. The bile is an 'intestinal irritant' and it can 'fast forward' things through the whole of your system. Bile can also reflux into the stomach and lead to symptoms similar to acid reflux.
Has your doc done an upper endoscopy to see if that's what's going on?
The other things I'm wondering about is if you've got any food intolerances since you mentioned floating fecal material and a rash. Have you been checked for intolerances to gluten (wheat, rye, barley) or possibly dairy?
You also might want to check with your doc about trying some probiotics. They might give you a hand with the gas. In some, they can take some getting used to, but they can be very worth it.
I have not followed a low fat diet. However, since you said something about gluten allergy, I did notice that eating pizza, breads, and pasta seems to make the rash and stomach bloating worse...oh and the smell of the diarrhea is awful. Sometimes it smells so bad, that my husband says it smells like rotting food. It is so embarrassing! Sometimes I do have undigested food in the diarrhea. Usually I will have diarrhea followed by constipation and then back to diarrhea. I also have terrible pains all over my stomach area and feelings sometimes sharp pain in the upper left and lower right abdominal area that are also sometimes tender to touch. It is so frustrating!
note: I did eat pizza this afternoon and I am currently up a few hours later because this rash on my arms is itching so bad. The rash usually flares up when I am having the flares of abdominal issues.