Ostomy output is floating in toilet, frothy, foul fatty smell, glistening and shiny/oily in appearance. possible causes?

Malabsorption: what you describe sounds like a failure to completely absorb in your small bowel. It can be from rapid transit, a lack of pancreatic enzymes or bile, small bowel pathology or from a bacterial overgrowth. This is more common with an ileostomy . It also may be related to your underlying reason for the ostomy such as Crohnes. See your GI doc or surgeon if it doesn't resolve soon.