I woke up yesterday and I notice that my rat had a huge bloody lump on his upper right side. It was not there the day before and it just appeared over night. I think it might be an abscess and I read that I should wait two weeks to see if it will clear up on it's own and of not then I should take him to the vet. He has been acting normal so far. He still runs and jumps and plays. I have never seen anything like this before so if anyone has any information I will gladly accept it. I will attach photos. Please and thank you!