Skin Problem

Question
My 18 month old rat has developed what looks like a small round lump in her skin (about 3mm diameter) that's scabbed over yellow and crusty, high up on her side near her back leg. The lump's isolated and her skin seems in otherwise good condition. She has a sister in the cage, and I don't know whether its just a war wound or something worse, otherwise she seems in perfect health and it doesn't seem to bother her.

Answer
Ia there any way you can take a photo of it?  You can send it to my email at Sandyscrittercity@yahoo.com.    It sounds like an abscess to be honest.  Try cleaning it using a warm cloth for a bit to get it to come to a head and after that, apply some antibiotic ointment. See if anything comes out of it by giving it a light press from under the lump and if so let me know what color the pus was.  It may be green, yellow or white and thick like toothpaste. It may have a bad odor.  Either way, let me know.