SKIN PROBLEM. Can you tell me what is that please?

[sherif_tarek]

Hi there, does this look anything familiar to you? These pictures were before and after applying isaderm on the borders of this allergy/hot spot thing. in it's first days, it was just a big red spot (picture 1), and then after 7/8 days of applying isaderm (picture 2 & 3), it became solidified, darkened and started being topped with hair, and borders have yellowish red crust.
P.s its not a burn and i have no idea what this is because we havn't done tests yet (there is an antibiotic in her body and doctor advised to do the test after the effect of antibiotic goes away)
Also she was spayed 5 days before this happened (no idea if it's even related), and never in her 2 year life she had any disease or infection or even a sneeze. Also after the spaying with 2 days for absolute coincidence i changed her litter for the first time to tidy cat lightweight-glade, because it was the only tidy cat available in store. (Again, no idea if that was related)

Can you please tell me what this is if you had something similar with your cat?
Thanks

[lilynmitz]

I'm afraid I have no insight into this except to say "Get her back to the vet asap!" This looks very nasty, and the existing treament clearly isn't working if you have seen no improvement after 7 days, and it's in fact getting worse. This needs further testing and alternative treatment. You refer to the "doctor" making recommendations - I assume you mean a vet? I do hope so...