why is my pet rat hoarding food and turning super aggressive

Question
QUESTION: I have 2 female dumbo rats, Sweet pea, who is blue and white, and Angel who is white. Recently Angel has become very aggressive with her friend. This began when I got them a much larger cage. Angel began hoarding food and she lunges at the bars if you get remotely close to the cage. She also tries to grab your hand and bite through the bars. Not nibble but bite with the intention of causing injury. She has only just began to act like this over the last few days. I have also noticed in the last day that her whole head seems to be swollen and she seems to not be seeing as well as she was. It appears that she has a scratch across the inside corner of her right eye. Could she have an infection? Please help me. She was such a sweet girl until recently and I would hate to get rid of her.

ANSWER:  Obviously something has occured that is causing a major disruption to her life. It could be illness but it could be the stress of moving to a new cage. Some rats react terribly  to a new cage at first, unsure what is happening. She is hoarding food in fear that the  food supply may not be available when she wants it. Do you feed them certain times of day or is there a bowl of food down all the time?   How old are they?

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QUESTION: They do have two bowls one on the first level of the cage and one on the third. one for each. But Angel takes all the food in a matter of 20 minutes, and then gets really mean if sweet pea tries to get near it. I fill the bowls once a day. and then refill them when they are empty. I got them both at Petsmart and i dont know how old they are when the store gets them but I would guess sweet pea is almost over a year and a half and angel may be a year. I have recently moved angel back to her old cage alone because she was being very mean to her friend. My boyfriend then bought another little girl we named Sasha because sweet pea was acting sad and missing angels company. Sasha is a baby for sure. Her and Sweet pea get along great and took to each other almost immediately. Angel has been in her old cage almost 2 days now and is just sitting in one corner and is still lunging at the bars. I am at a loss for what to do.

Answer
Check out my website, sandyscrittercity.com and read up on working with shy and biting rats.  It sounds hormonal and although I am hoping this is what it is, with them being pet store rats, they could be inbred beyond belief as they often are.  Give her all the patience you can muster. I know this is hard, but do NOT let her know your scared or concerned by her behavior or she will focus on this negative energy and feed off of it.  Talk softly to her, take her in another room for play time, letting her come out of her cage on her own, reward her with a treat when she doesnt bite, but if she acts aggressive toward you, put her back in the cage with no treat. She will catch on if she wants out to play bad enough.  She needs a set up for play time all of her own.  Check out GETTING STARTED to read on making a play area for rats so they can  feel secure in their own surroundings with  things meant to stimulate their needs. She needs this more than anything right now.