@itachi8sasuke99,
Well, I hate to bring up the obvious, but have you considered bringing this kitten to the Vet? After all, that should be a normal part of care-taking of any pet.
At what point was it weaned from its mother? Was it at more than 6 weeks old, (hopefully)?
Does the cat have diarrhea? Does the cat have a decent appetite? Is it competing with other cat's or kitten's for its food?
The problem could be something as simple as having made a sudden change in the kitten's diet or being advised that a change is needed. Be aware that a kitten's diet is vastly different from an adult cat. Either way, a vet most often is a good detective and can advise you about the trouble far better than we can.