I have a chicken that has a growth on one of her toes. It is about the size of a large marble. She hasn't seemed bothered by it until today. She is now limping and trying to not walk. It has three small dark spots on it that look like sunken in scabs. We had a mouse with a bot fly larva in our coup a couple of weeks ago. I thought maybe that was it. Today I tried to squeeze it to see if it would rupture, but it feels pretty solid. What should I do?