My hamster has a weird skin condition....

Question
My name is Yara, I'm 12 years-old and I have a hamster I love a lot. I just noticed last week that he's staring to look different. He's a "Russian Hamster", I'm not sure if that's right. But his skin seems irritated and he looks so poofy without hair, as if he's allergic to something, like when my sister's eyes get all puff when she gets a strong allergy reaction. Also one of his paws seems bigger than the others, he's also bitting himself and taking all the hair out himself, at least, that's what dad said. I'm looking around in the Internet and came about this site, if you could help me, I would appreciate it. I'll continue to look around.  

Thank you so much for taking the time to read this.

Yara =^_^=

Answer
what type of bedding do you use? hamsters can be allergic to certain bedding especially wood shavings. I use carefresh bedding because it's more hypoallergenic. Ceder and pine cause allergic reactions in hamster and they will lose their fur and itch a lot. Also, is the hamster skin red and flakey? If so the hamster probably has mange mites and will need to go to a vet for treatment for the mites. I hope i've helped you. Also, think of what you have done differently right before your hamster started losing fur, have you used a new bedding or something?