Illness or Injury
The best advice that can be given if your hamster is ill or injured is to take it to a vet! Ether one that is good with rodents or one who is knowledgeable on 'exotics'. It is best to get your hamster there as soon as you possibly can at the first signs that something is not right. The vet will be able to diagnose the problem and know the best cause of action to treat you little one. Because of the living conditions in the wild, hamsters naturally hide any sign of illness and infection to the last moment, so if there are clear signs act on them, waiting could make it too late.