Had viral gastro. Week later feeling full easily and bloated. 1 small bowel movement since. Mostly watery stool. What can it be?

Bloated. You may have paradoxical diarrhea where you have fecal retention and you get watery diarrhea around the constipated stool. You may nee enemas to clear up your constipated stool.
Help GI tract. Mwy want to consider probiotics to replace normal flora of colon.. If persistant see your doc.