He might have a parasite, you should bring him into the vets, where did you get your kitten? Might also be a tape worm, but unsure, please bring your kitten in for an evaluation. Blood work might be done as well. Good Luck
This could be due to dietary indiscretion, intestinal parasites, anal gland issues, or a bacterial overgrowth. Your cat needs to be examined by a veterinarian. A stool sample needs to be examined as well. This is not normal and your cat needs medical treatment.
I don't know but you shouldn't let him lick there