Female rat favoring front right paw.?

Late last night I took my girls out to watch some telly with me and I noticed one of them was walking a little funny. I picked her up to check her out and I noticed she was holding her right front paw close to her body. At first I thought I saw a little cut/scratch on her arm so I put neosporin on it and just left her to snuggle in my pillows while I went to make her cage a little safer for her. Well I just got her out a little bit ago and she is still limping and the 'cut' is gone. So I checked her arm as much as she would let me and I don't see any sores or scratches or anything. The whole thing is a little swollen, she is hardly using it to walk (just to keep her balance), but she is using it to hold her food. Also she squeaks when I touch it sometimes. If anyone has any suggestions, (besides going to the vet if there is no improvement by monday we're going) please let me know. Thanks.