Angry rattie

Hi there, looking for some advice. One of our girls (appx. 7 months old) has over the last 2-3 days become very aggressive. We’ve had her for a while and she has always been very sweet. Now, she’s charging my hand and lunging to bite me anytime I’m within 2 feet of her. I can’t think of anything I would have done to scare her or create such a negative association in the last two days. As well, it’s not like I’m poking at her or getting in her space; I’ll be cleaning on the bottom of the cage and she’ll run down 2 feet to try to bite me. It’s making it hard to interact with the other girls. She is not acting too badly towards them, but she does seem to have a problem outside of the cage as well, so I’m inclined to think it’s not territorial. Do you think she could be sick? What should I do? I’ve never experienced a turn of behavior like this before and it’s sad and worrying.