NuvaRing and severe endometriosis

My 16 yr. old daughter is being treated for severe endometriosis with the Nuvaring. Started wearing it after first surgery, last May. She wears 3 rings over nine weeks, then has a period for a week. She started having lower back paing that interferred with her life in July or August. By her second surgery in Feb.'06, back pain was debilitating and she had to leave school and switch to home school because she is mostly bed ridden. Every movement causes her tremendous pain. She is currently taking five meds for pain, including morphine. She can bearly walk. Doc (GYN) says it's not related to anything in his department, yet MRI, bone scan, x-rays, blood test are all negative. While we are pursuing further testing, I believe that the ring may be responsible for this. So far there are no other explanations, and the research I have done so far is pointing in that direction. My once vibrant, active happy, college-bound teen is now 25lbs lighter, severely depressed and in constant pain. I hope it is something as simple as discontinuing the ring, and I hope that little ring hasn't been the source of her suffering all this time.