my unspayed female cat has a large lump on her chest. It's hard to say how big exactly, around the size of a ping pong ball I think. It seems to be right under her teat, but I don't know if it's related. She doesn't have any cuts or noticeable wound, is not scratching or licking any more than usual. This lump was not there a few days ago. It does not move, and does not seem tender. She is acting totally normal.
Any ideas? I know we should just go to the vet but if I need to be sure its necessary because the expense is a problem (also why she hasn't been spayed yet.)