Am I reading correctly that your cat did indeed have fleas when he was licking his fur out (possibly caught from the vet visit)?
Do you know if he currently, 100% free of fleas?
My first thought is a hypersensitivity to fleas (allergy).
After the rabies vaccine, did your kitty develop a lump at the injection site?
Is your cat still eating, but loosing weight, or has your cat stopped eating? Did the vet do blood work before surgery, or when you took him back?
Cat maid to:
Jasper, male Ragdoll ?? (approx 10 yrs)
Sweet Pea, female silver tabby DSH (approx 8 yrs)
Rose semi feral, a cpietra rescue, female tabby (approx 7 yrs)
Puddles RIP (1996-2014
Snowball RIP (1991-2005)
In a cat's eye, all things belong to cats.-English Proverb
“While we are free to choose our actions, we are not free to choose the consequences of our actions.” Stephen R. Covey