What color are the bumps?
This sounds like miliary dermititis from what you are describing. This is a skin condition where the cat will have crusty bumps anywhere from covering their whole body to just in one area like your cat. There can be several different underlying causes of miliary dermititis. It could be a bacterial skin infection, allergic reaction , flea bite sensitivity, or more. Here is a link to a page about this:
I'm glad to hear you are taking her to your vet soon as that is the best course of action. You don't need to do anything for her in the meantime. If she should develop any additional symptoms such as loss of appetite, or lethargy then you should get her to a vet right away.
I'm also going to give you a link to a page that has a chart of different skin conditions in cats in case I'm not getting your description right, sometimes its difficult when you can't actually see the problem:
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I'm sorry, its difficult to figure out skin conditions on-line. If you think the growths are too big for miliary dermititis another possibility are mast cell tumors. Some are cancerous, some are benign, but you do usually see more than one in an area. Here is a link to a page about these:
One thing you could do that won't hurt anything until you go to a vet is to try an antihistamine for your cat. This will help to determine if its an allergic reaction. Chlorpheniramine (chlor-trimeton) is one that works well for cats and is safe. The dosage range is 0.1-0.2 mg per pound of body weight twice daily. If this is going to help there will be an improvement fairly quickly.
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