Why is my hamster so scared?

I got a golden hamster in May. The pet store said she was a few months old (about 4) and had been there a while, i felt bad so i brought the little stinker home. When i got her home she would always bite me so i started to pick her up using her hut. She trys to jump out, or jump out of your hand. She has stopped biting, but now she runs away from me wheni try to pick her up. she has fallen 2 times from slipping through my hands, once was into her cage onto the bedding adn the first time was onto the carpeted floor. She seemed fine after she fell, but i dont understand why she is scared. Even if i got her in my hands adn she is fine and still, she flips out all of a sudden adn trys to get out of my hands