Bitting problem

Question
I was wondering if you could answer my rat question? i have 6 rats at the moment but one, has started bitting me, she started bitting me a week ago, i have asked so many people for help but no one seems to be able too help me, so i was wondering if maybe you could help me, as i said it started a week ago, and i went to pick her up and she bit me, so then i went to get another rat out instead, but as i reach to pick up one of the others, she came up and bit me, at first i thought she was just being territorial, but no i got her out with a cloth and put her down on the floor, then she came up to me and bit me, now i can't really do anything in the cage like clean it or give the bowl more food, without being bitten, i have tried sqwirty bottles for when she bites and treats for when she doesn't bite, but that didn't quite work because there hasn't been one time i haven't been bitten by her when i am near, what can i do? is it a medical problem? a faze? i really have no clue so i hope you can help she's never bitten anyone before in her whole life.


Answer
How long have you had her and how old is she?  Who does she live with (how many females to the cage etc...)  

Also, I am afraid that using the squirter bottle method has made  her not trust you and she is feeling negative feedback from you because of that. Rats do not understand discipline and instead, they see it as negative energy and become fearful.  Fear in turn makes a rat bite. This may have made it even worse and now you need to earn her trust.  using treats as a reward is good, but you must be consistent with it.  

Tell me about her play time out of the cage.  I need to know as much as possible about her life in order to understand where she is coming from.  When you first got her, did you get all six rats at once or did you buy them gradually....tell me the story of how you first brought her home and if she had cage mates to meet or if she was already a member of the family and you brought new rats in etc....