NEED ADVICE..Cat is fur and bones,not eating much and no longer wants dry food?..?

Sounds to me like he probably has fleas. That would explain the licking and nibbling. If this is the case, then he probably ate an infected flea and may have intestinal parasites.. they're not USUALLY a huge issue.. until the cat stops eating. Treat him with some Advantage flea treatment and then take him to the vet for a de-wormer.. and if that is indeed the issue, it will clear up.