Question, I got this kitten as an abandoned one. when I got him, i noticed that he had a big belly, so i wormed him, this was abotu 2 weeks ago. The big belly has went away now, and now i notice that he has an upset tummy.
Did you buy over-the-counter de-wormer or take it to the vet? If you used OTC de-wormer, maybe you used too much for his/her weight and if so I can well imagine they have an upset tummy.
Please take him to a vet to be checked out. When cats are in pain they don't show it and it would be awful to know he/she was suffering.