Bald spot and a litte darker skined

[lovelyhamsters5]

My longhaired Syrian hamster, Einstein has a bald spot on his back right where his shoulders meet behind his head then the skin there is a tiny bit dark but I'm just wondering if I should be worried. Though he is still very active, loves to eat his food and his occasional carrot treats I give him, and he loves to drink his water. He pees and poops normally and has finally gotten used to peeing in the same corner all the time. Also everything else from his eyes to his tail look fine and he is about 4-5 months old. His bald spot has been worrying me. My boyfriend said it might be genetic because we got him from a pet store so we don't know his genetics. I am just wondering if there is anything serious that could be causing this (and if so what are the other symptoms) or could there be a possibility it's just natural.

[cypher]

Not really sure what might be causing it but small patches like that can be caused by rubbing against something in the cage, have you checked the cage over (& everything in it) just to make sure?
What kind of wheel do you have, it's possible his hair may get trapped in that when he runs which could cause a bald patch over time.
If you could post a photo it might help give a better idea of what might be going on.