Poor kitty. It seems suspect to me that it is spreading to the other ear, and that three vet visits come up with the same solution....antibiotics.
My Otis had a crusty ear that was determined to be an infection. The vet cleaned off the crustiness and gave him an antibiotic shot (no need to pill him). It sounds like you've tried that route already. Can you clean off that crustiness, or is it part of the ear itself? Maybe you don't want to mess with him too much. He sounds stressed out.