Hello.. It sounds to me like it's feline acne, although I don't know what vet would not recognize it...
Feline acne can be caused by stress, allergies, skin conditions, poor grooming habits, etc.. It looks like little black heads on the skin, and cats will scratch and they will ulcerate and be icky. Many cats develop an allergy to the plastic bowls they eat/drink out of. If her bowls are plastic I would switch to ceramic. You can get an antiseborrheic shampoo at your vet to keep the area clean. Vets will also give antibiotics and pred, which you say she's already had. Have her tested for yeast infection, demodex, and ringworm if she hasn't already, these can all cause kitty acne, and be very itchy/painful.
Hope this helps :)
What I mean is under her chin...around the bottom jaw. The vet has put one of those cones on her so that she cannot scratch. She did not have tests but he treated her with antibiotics( she scratched a lot) and with pednisone for the itch. The vet checked for mites and fleas. We are going to the vet again on Friday for a checkup at that time he will clean the area around her eye and determine the next step. Just wondered if anyone else had similar things with their cat? We did change our fabric softener and I put a flea collar on her a week or so ago however I took the collar off as she seemed to get worse after that.
Do you mean nose, when you say muzzle?? I think that's what you mean. Has your vet done a skin scraping?? That is very important, and that could tell you a lot. I agree with Savas with stress, and cleaning products possibly being the culprit. Think about what's changed to cause stress-cats don't like change of any kind, they like to feel secure. Example-are you not home as much anymore, have you moved, do you have a new cat? Plus many more will stress a cat out. This is only a possibility. In the meantime, I would trim kitty's nails down some, to keep her from doing any more damage. Just don't go to short, cuz you'll draw blood.
Has the vet done any other tests-blood work? If so, what did it show?
I mean black gunk under her muzzle it seems hard and crusty.
Do you mean black "skin" or black gunk?
Excessive scratching is usually either from bites, stress, or a skin condition. Causes tend to be environmental (cleaning products used about the house, sprays, etc) or food related.
It is possible it could be caused by an ear hematoma as well...but I'd need a better description of what the black is to say.