My cat has a bald spot and I don't know why...Please Help!!

This is Sully. He is almost 5 years old and has never had any problems. I just noticed tonight that he has a bald spot on his back around his neck. He is acting perfectly normal and hasn't shown signs that it is bothering him. He does have a brother that he fights/plays with sometimes, but this spot doesn't look like it was caused from that. The vet is closed and tomorrow is sunday so the hours are limited. I have no idea what caused this. Can anyone help?

Thanks!!

This isn't an emergency so you're ok to wait until you can get an appointment with the vet

I'm not sure what the bald spot could be. Do you use a flea treatment or preventative such as Advantage? If so, the bald spot could be an allergic reaction. My Aby got bald spots on Revolution and those spots weren't even near the area where I applied the Revolution. The bald spot could be an allergic reaction to something in general: food, maybe he got something on the fur, hot spot, etc.

Could he be scratching or licking it?  My cat had a bald spot and some scabs on his back.  I didn't think he could have done it to himself since he couldn't reach, but boy is he flexible. 

We had a kitty when I was growing up who had skin allergies. He never had a problem with fleas, but he would get so itchy that he would lick and scratch himself raw. We had to get him cortisone injections every six months or so. It was never an emergency and it never led to anything worse. Hope this helps and that your kiddo gets a good report!