she had brainstem cancer at 4. now 23 has radiation tumors?

Ok. My sister was 4 when she was first dx with cancer of the brain stem. They told her she sould not live past 6 mths and shes now 23 and has three kids. The past five mths shes been having severe headaches and memory loss , dizzness, limping, and severe mood swings. She had an MRI and it showed something by where the orginal tumor was. She almost had brain surgery to either biopsy it or remove depending on what the results were. As soon as we were saying our goodbyes the dr. came in and said he didn't think it was a tumor and wanted to "watch" it. She's had MRI'S done monthly and still no answers. She went to Indy today for answers but the dr said she didn't know what they are. Now she has more. The dr said she thinks they are called radiation tumors and wants to wait 8 wks for ANOTHER MRI and between now and then a spinal tap. Its been five mths since, she's been in the ER almost every other night for headaches and still no answers. They are saying that the spots are all over. My question is.. has any of you heard of anything like this or radiation tumors? Every dr has been saying thry don't know what they are.. were tired of no answers and just want to move on with either treatment or something. Can anyone please try and help??