Hi and welcome to TCS. I can't see which areas are losing hair. Does he scratch a lot? Does he overgroom? How long has it been going on?
It would be best to get a vet to check it out especially if there are any other abnormalities or new behaviors. The hair loss could be from allergies of some type, but it's impossible to say.
It's been going on after I took off his collar cuz I notice he was destroying it bc of his scratching and it looks way bad now I have a vet apt on the third of next month but what do I do till then