I am sorry to hear of your troubles with your little Hammy friend. I myself have a little hamster as well. I doubt it was anything you did, sadly due to over breading and inbreeding this happens. If you would like to talk about it, pm me. Or you can always check out the forum Hamster Hideout - http://hamsterhideout.com/forum/ -they are a wealth of knowledge on Hamsters and a very friendly community willing to help in any way they can as well have a special place for those that have crossed what they call "The Rainbow Bridge"