patches of skin on cat

Question
My cat, (who is over 5 years old and has no known health problems), will occassionally, usually overnight, scratch/lick a bald spot on the back of his neck (the same location where a flea medication is typically placed).  I haven't used flea medicine on him in years, since we haven't had a flea infestation in quite some time. Is this a skin problem or a behavioral problem? He is very difficult to get to the vet (becomes very agressive/violent).

Answer
Sctratching the neck and getting little bumps in that area is typical of allergic skin disease in cats. He could also be scratching at his neck because of ear mites.  Have the vet check him out for you.  If the cat does not like going to the vet, ask the vet for a tranquilizer tablet to give about 2 hours before your appointment.  That way, he will not be as excitable and it will make the exam easier for the cat and the vet.