Did the vet hurt my chin??? Huge bald spot after seeing the vet and eye infection. Picture

Hello. I took my chin to the vet yesterday because his eye infection will not go away. They told me there is nothing else they can do (they only prescribed one antibiotic, terramycin ointment) and dexamethasone steroid drop. They told me to use the steroid from now on. That evening, I noticed when my chin ATTACKED me and hissed at me that there was a large bald, moist bald spot below his chin. He has had an eye infection for a while that I was worried might be fungus, so I'm not sure if this...

Did the vet hurt my chin??? Huge bald spot after seeing the vet and eye infection. Picture