What is wrong with my cat?

Hey, my cat has had this spot on his neck for two days. He's four years old and a regular house cat. He doesn't go outside, so he's not an outdoor cat. He has no contact with other cats (he's a single cat and is traumatized by other animals, especially cats). He doesn't scratch it either; he just licked it at first. The hair falls out around the spot. He eats a healthy diet and drinks normally. He only vomits sometimes because he's greedy and eats everything he can find. Do you perhaps have a cat who had this or something similar?

I know you can't see much but I can't get any closer to the spot