Lovatos got a massive lump =(

Question
My friend directed me to you, so I'm really hoping you can help me. My 4yr old rat, Lovato has developed a massive lump under her arm in the last week or so. I feel like a horrible pet owner because I can't afford to take her to a vet for another week and a half when I get paid. I know she is suffering because every time she moves, she squeaks in pain. I really don't know what to do, even to just make it hurt less until I can get her to the vet. Any advise you have would be GREATLY appreciated.

Answer
Well it seems to me that your female has a mammary tumor, this is fairly common for female rats, and because of her age you can either decide if you want it removed or leave it.. It will how ever get bigger. but it won't do her any harm other then sight wise.  But take her to the vet and see what she says. but it sounds like mammary tumor to me.