Advantage II is the stuff. Flea treatment. $46 for two months.
Cat won't let me get much of a look at his underbelly, but he's doing a lot better, I can tell.
My local cat will let me pet him, but not pick him up or put a collar on him. Lately he started scratching even more than usual. Where he could lick, his black hair turned a brownish color. I got some of the drops you put on the back of their neck, at great personal expense. Seems to be helping...