Recently just got two new female rats off facebook for my single female whos cage mate passed about a month ago. I kept them in separate cages for 2 weeks while introducing them and ended up buying a double critter nation for all three of them. I have been leaving her alone to figure out her way around the cage and she has not been out for about 3-4 days. Finally, last night I took her out to play and realized she had a large hole about the size of a quarter on her lower abdomen (or vagina honestly can't tell) it is hollow and I can see inside of her body. She is not bleeding, just licking the wound occasionally. She is eating and drinking fine and behavior is normal but I am freaking out. All of the rats get along and there has been no fighting. Just wondering if anyone knows what this is and if I should separate them.