a few problems with my hamster

Question
Hi there. I just bought a dwarf hamster from a local pet store. And I don't have too much experience with hamsters,so I was wondering if you answer a few questions for me. I apologize ahead of time if I ask too much.

First off, the people at the pet store didn't seem too know much about animals sadly,let alone hamsters, so they were unable to sex the hamster. And when I try myself, he/she is far to fidgety to get a good look. So I ended up going for a unisex name [Mosely] But I just don't feel right not knowing what he/she is.

Also, Mosely does not seem to be eating or drinking which really concerns me. He/she spends most of his/her time sleeping in the top level of the cage,which is much smaller than the bottom level, which I also find quite weird.

And finally,i've noticed Mosely appears to be chewing at his/her behind. And I was just wondering what could be wrong.

Again I truly apologize for asking so much. I'm just very new to this and don't want anything to go wrong. Thank you by the way. =]

Answer
It is harder to tell on dwarf hamsters what sex they are. But if you can get a look at his stomach, their will be two holes under his/her tale. If the holes are farther apart, rather than right next to each other, then it is a boy. If the holes are closer together then it is a girl. Hamsters like small places when they sleep, it makes them feel more cozy. The eating and drinking problem is probably just because he/she is adjusting to his/her new enviroment. Just try showing him/her where the water/food is. Most likely Mosely isn't chewing, he's cleaning his fur. This can look like chewing, but its not.

Thanks for writing