Kitty Acne still not going away

Ok, Mattie has tried:

*antibiotics (she was on a 7 day course of amoxicillan)
*cerumene / chlorhexidine scrub 2x a day (the cerumene removes wax buildup and the chlorhexidine is to clean)
*brand new, sterilized stainless steel bowl or ceramic dish for each feeding
*cleaning water fountain every day

Now the blackheads are actually starting to get infected. Today when I wiped her chin, there was blood. She looks so messy, her entire chest area is so dirty looking because of the residue from the chin (she is a white cat, so it really shows).

What else could possibly be causing this? I know that she might just overproduce that waxy substance or the oil, but after google searching I figure it can also be:

*food allergy
*yeast infection of the chin
*mange
*staph infection of her chin
*ringworm

Are these things that the vet would have necessarily caught the first 2 times she saw her? Is it very likely that this is a food allergy, and if so what should I try eliminating from her diet? (she eats Nutro Natural Indoor Cat food and a variety of wet foods - Nutro Natural Indoor Pouches, Natural Balance Indoor and Solid Gold as a treat every week). I've posted a thread about her stubborn acne before but now I'm wondering how likely it is that it's something else?

(I have a vet appointment for Mattie on Friday)

I don't mind cleaning her chin everyday, even though it makes her super grumpy (as if she wasn't grumpy already). I'm just frustrated that nothing is making this go away. I want to take her to a groomer SO much to at least clean her up because she looks super dirty (I am not even going to attempt a bath, lol), but I wanted to wait for this to clear up.

What kind of water dish do you have? My dear Penni (RIP) had acne on her chin, but not so severe that we went to the extent you have to resolve it. However, I was overjoyed when we got the cats their Drinkwell fountain - the acne almost immediately cleared up!!!! I attributed it to the fact that the water was filtered.

And also, I had a friend whose kitty had the same problem, like Penni, only a mild case, and the vet said to change from a plastic water bowl to a glass/ceramic one, and to make sure the water was changed frequently. I'm pretty sure that cleared up Bert's problem too. Unfortunately, she crossed the rainbow bridge a while later from Vaccination Related Sarcoma

Have the vet culture it ///

Chicken is a common one in all the foods...

since your using INDOOR it has some soy ...

When she was on the amoxicillan did it clear up? Veeshan gets chin acne real bad. I use a wash cloth and water and scrub the black stuff everyday. I do not have plastic bowls. Also my vet prescribed Clyndamycin (tissue antibiotic) that did clear hers up but it did come back like after a month. Right now Veeshan's acne is very minimal. Makes me wonder if weather has anything to do with it.