So 1 year ago I applied bravecto flea treatment to my cat and he had a horrendous reaction, he scratched so severely he made the skin at the back of his neck raw (shown in the 1st picture). I took him to the vet and they prescribed a steroid cream and anti-itch tablets. This worked up until his skin scabbed over and he kept scratching the scab off, and taking him back to square 1. I tried having him wear a cone, donut, vet vest, none of these prevented him from scratching until I bought a harness and it prevented him from scratching his neck. From that point on he hasn't had any flea treatment (he's an indoor cat so less likely to get fleas/parasites so I took the risk).
A matter of days ago, I figured I'd apply advocate to his neck as it's getting warmer and I take him outside for controlled enrichment (I live on a main road), and he's now scratched his neck and between his collar blades raw. I can take him to the vet to get the same treatment but I'm literally going through a cycle with him. I don't know what to do. I even changed him to Royal Canin Hair and Skin Care food to help. Is he allergic to both advocate and bravecto? Does he just not like the sensation, I mean this cat will keep scratching until there is bone if I let him. I have to constantly keep an eye on him.
Is it a behavioural thing? Even when his skin was fully healed he would go back into scratching himself raw.
Fortunately I have insurance for my boy but I need to know what's going on because I care too much about him.