Have you tried giving Homer a bath in betedine soap? Just an idea - it helped BamBam’s allergy. Also, that green algea stuff which I can’t remember the name of right now works sprinkled on food sometimes. That worked for Sonny’s allergies to the world.
We have a medicated shampoo - we gave him one today, as a matter of fact. I don’t know a thing about the seaweed stuff... what’s that?
Spirulina. I tried that with Tuffy’s allergies but it didn’t work. Turned his lips green, too.