Welcome to NeuroTalk:

Your post is quite confusing.

Can you tell us what that supplement was? The name of it and
the ingredients in it?

People with upset GI tracts... may improve with a probiotic, or Kefir daily. Kefir is very good at stabilizing GI status, which can get messed up with antibiotics, etc.

Watch what you eat, and eat whole foods which are bland , avoid too much sugar or bread/carbs, avoid spicey food, MSG, or processed fast foods for a while. Floating stools indicate poor fat digestion or too much fat intake.

Can you put on this thread a list of supplements you do take?
Bodybuilding people tend to take all sorts of things, in high doses, and some of them may not be safe. When you swallow a tablet or capsule you should use plenty of water. If you do not the capsule may lodge in the upper stomach near the esophagus and dissolve there, where the cells are less protected...this can be very irritating and set off reflexes of pain. (hence the Barrett's esophagus).