Bleeding lumps & small patches of fur loss on cat?

Hi I'd really appreciate a qualified vets opinion on this. My cat has been developing small patches of fur loss within which are raised pink lumps which then bleed (and sometimes weep) then scab over. She had antibiotics a couple of weeks ago which seemed to clear it up but fresh patches still keep developing. My vet said it could be an allergy to Iams dry food but she's been off that for over 2 months now. She doesn't seem to scratch the areas or be particularly bothered by them and isn't behaving abnormally in any other way (she's not off her food or less active). What could this be, is it serious (my vet doesn't seem to think so) and can it be prevented/cured?
Answers:
It does sound like an allergic reaction, but it doesn't necessarily have to be to the food. Cats can be allergic to the same things we are...dust, pollen, mold, etc. However, instead of showing the allergy in the eyes and nose like we do, dogs and cats show it in their skin. They get itchy, scratch and get secondary bacterial infections and the hair comes out. Injections of Depo Medrol will relieve the allergy symptoms and antibiotics will clear up the infection. With luck, your cat has a seasonal allergy and will get better when whatever it's allergic to goes away. A second Depo injection may be needed in about a month or 2, depending upon how the symptoms clear up. Mites in cats usually affects the ear flaps the most and they become very scaley and crusty. Fungus (ringworm) can also cause hair loss, but not usually the secondary bacterial infection.

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im not a vet but it sounds like mites or some kind of bugs or parasites

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mine had that too, he had to get a shot, um... let me find the paper. ok its called depo medro and it all cleared up. Its like some skin bacteria.

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Are the lumps very small the size of BB's? Are they initially the color of the skin, then turn red and scab up, with the scabs disappearing in a week but more lumps appearing? Are the lumps on the neck, shoulders, sides and lower tail (where it attaches) but not on the legs, belly or upper tail?
My cat and two others on one of our cat lists had this immediately after a pet foods manufacturer 'tweeked' their ingredients in the Royal Canin Siamese 38 brand food. There were literally hundreds of lumps appearing on our cats, and we didn't know what was going on, didn't associate it with the food change till we compared notes and found that we'd all just gotten a new bag of the 'improved' version of the food. It turns out that we had some cats who were EXTREMELY sensitive to rosemary extract.
They put rosemary extract in most cat foods--it's a natural preservative, but Royal Canin had moved theirs up about 3 lines (meaning they added a lot more to the mixture) and our cats immediately developed these lumps within 3 days on the new food.
If you think this may be the problem with yours, all it takes is to get the cat off whatever food you're giving and look for a brand who puts the rosemary extract WAY down the list. You should see the lumps going away within a week.