What could be causing this?

Hi everyone, new here.

I have a longhaired cat that is about two years old. His name is Chill Bro, but he is actually the most anxious cat ever.
I fostered him as a kitten and then adopted him. He became anxious after the animal shelter neutered him, I think they may have not used enough painkillers or aomething because he was wide awake and panicking when he got back, which I've never seen before. Anyway, I've done the best I can managing his anxiety short of getting meds from the vet (which I'm considering), and he has always been ok. Lately though he started licking all the hair off his hind legs, I assumed this was just anxiety but even more recently he has suddenly gotten scabs on his head above both eyes. I assume he is scratching too hard, bug I haven't witnessed it myself.
Before anyone says, I plan on calling the vet tomorrow, they aren't open today. I have been hesitant to take him because he is so anxious and I don't want to cause him any unnecessary stress. I wondered if anyone has dealt with a scenerio like this? Could this just be anxiety or is it something else?
I use feliway difussers and we recently switched food to Canin SO due to our other male cat getting crystals in his urine (that was a terrifying ordeal let me tell you), but the hair licking started way before the food switch.

I just want him to be ok, he always seems to have something wrong with him

Here are some pics

That looks like fleas or a severe anxiety problem. If your vet says it's stress/anxiety related prozac maybe in order. Good luck! I hope he heals as soon as possible.