Hi again, and thanks so much for the additional information!
There are various causes for the types of bumps you're describing, and the first possibility is external parasites (fleas, mites). Even though she's an indoor-only cat, she can still get fleas wich can be brought into the house on the shoes or pant legs of humans. Some cats are very allergic to flea bites, and it just takes one for there to be a skin reaction as you describe.
There is a type of dermatological condition which causes rough, sandy-feeling bumps/lesions on the cat's skin, called Feline Eosinophilic Granuloma Complex (ECG). This can be caused by food allergies, flea bite allergies, or an auto-immune type problem within the body. Some vets will treat this with antibiotics to guard against bacterial infections, especially if some of the sores are open, as you indicate.
The pink belly and her biting and chewing in this area may be caused by allergies, or may be an obsessive-compulsive related condition. Some cats just start biting/chewing in an area (the belly and inside of the thighs is very common) of the body and there's no real cause. This behavior is usually classified as OCD in nature and is successfully treated with a steriod like Prednisone and an antihistamine to minimize the itching/skin irritation. Some cats are just more prone to this than others. Sometimes it occurs occasionally, as you've described, and other times it happens on quite a steady basis.
Also, if a cat starts licking/biting/chewing excessively in an area like the belly, it could be due to an (internal) intestinal problem, kidney or bladder problem, or anal glands may need to be expressed (emptied). The cat will lick in that area, because 'something' is bothering her inside, and she can't 'get' to the area to relieve the discomfort. From your description, I think this is less of a possibility, but no stone should be left unturned.
I believe the best thing you can do for your furry girl right now is bring her to the vet to be evaluated and the proper treatment will be prescribed. Also, discuss with the vet if it might be advantageous to apply Advantage or Frontline monthly, to make sure she won't be bothered by flea problems. If she has any bumps/sores in the areas of her neck, right behind her head, you won't be able to use Advantage, etc., because that's where it's applied.
The fact that she also defecated outside the litterbox may indicate a physical or behavioral problem, since this was uncharacteristic for her. Make sure to mention that to the vet, also.
I hope all goes well and please keep me updated on how she's doing and let me know what the vet tells you. Thanks!
Cher
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