rat mammary tumor

Question
It looks like our rat has been chewing on the lump in her groin.  It is ulcerated and getting bigger.  Would it be OK to treat her with hydrogen peroxide?  I don't want to spend money on a vet. Is there any antibiotic we could buy over the counter?

Answer
 Hydrogen peroxide won't help the problem, and the burning sensation it causes will probably make her chew on it worse.  I'm afraid there really isn't anything you can do except take her to the vet.  Antibiotics are not available over the counter, only by prescription.  If you don't want to spend the money I suggest you have her euthanized as she is obviously in pain and is suffering.  I'm sorry, but there's not really anything you can do yourself.