Do they look like red bumps?
Red itchy bumps may be caused by a bacterial infection, ringworm, red mange, scabies, and food allergy. For ringworms, apply an antifungal, like Savas said. Anyone will do, so yes, those over the counter creams will work.
Some diseases, like ringworm can be treated successfully if caught early but prognosis may become poor in advanced cases. So, it is vital that you seek help if the antifungal cream doesn't work, because if it doesn't, then you're dealing with something else far more serious.
If there are other pets in the house you might want to either isolate this one until you know what you're dealing with or ask the vet about this and the possibilities of it being contagious.
Good Luck.
It sounds like ringworm. Try an OTC anti-fungal cream like lotrimin. If it is ringworm, it will clear it right up. If not...
Take kitty to the vet. Keep in mind in some cases ringworm is transferable to people (trust me, I know). While not dangerous, it's irritating.
Twice daily with the cream, be sure to work it in fully. If there's no signs of change in a week, then a vet visit is needed.
My first thought when I read your post is that your cat has fleas, especially from the location of the sores. Your cat could be allergic to fleas and is traumatizing his skin in his efforts to catch the fleas. Do you use any flea treatments?
It could be due to cat fights so you want to watch for any swelling which is indicative of abscesses.
Have you seen your veterinarian yet?
You could also try to put a child's t-shirt over him to try and get him to stop licking, but it sure sounds like he might need a veterinarian's attention.
Good luck!