Dark Red Patch, Burning Sensation, Pain In Lower Back. Worried, Any Solution?

Hi, my mother has been suffering pain in her lower right back, she has experienced a burning sensation and there is a large dark Red patch in the area, looks like a bruise , she has had this for about 2 months. My mother has had cancer twice and I am worried I have searched on the Internet and can not find anything, she has visited her doctor but he hasn t really said much on it, there have been no checks or anything. Do you have any information that might help me, I am sick with worry about this. Thanks