Recent Balding above tail!!

Please Help Us!

About a month and a half ago I noticed a white spot on the top of my outdoor cat's behind, I let it go because I thought the hair was just pushed around. About a week later I noticed the spot got a little larger. For about another week I watched my cat and the spot. I didn't notice him overly gnawing scratching himself, but the spot got a little bigger and a few other spots on the side of his hip started appearing. And when I try to get a close look at it and touch it, he either moves, growls or runs away. I took him in to his veterinarian and she told me he was getting bitten by fleas since she saw a FEW on him. She told me to put some Advantage on him and it would get better. Although it has only been a week since I put the Advantage on him, I am still concerned because not only is it not getting better, but it is getting progressively worse. Plus, I have not noticed any fleas of him or my other cat.
Additional Info:
His mood isn't changing, but he has pooped a few times on the carpet in various corners of the house, and once right in front of my boyfriend.

What do you think it could be, and what should I do?

I'm not sure how I missed this thread. Sorry for taking so long to reply.

If you're positive that the fleas are gone and the bald spot isn't an allergic reaction to the fleas, then your cat could be allergic to something else. My cat Creamsicle had the same thing except that it spread to her tail and all along her spine and head. She lost so much hair that her tail looked like a rat's tail. She's now on Prednisolone because we haven't been able to determine what she's allergic to and the itching was driving her mad.

It's a good idea to take your cat back to the vet and explain the situation or you might also get a second opinion. Has your cat lost more hair since you posted this thread? Also, seeing that it's an outdoor cat, he could be allergic to all kinds of things.

Good luck and let us know how s/he's doing. :)

Hmmmm.... other than a flea allergy my 2nd guess would be anal sacs. If they are bothering the kitty, he will lick his backside (in private if he's shy). Might also explain the pooping if his pooper is uncomfortable.