stomach/leg pain in 7 year old

Hi, I'm a mom at the end of my rope. My child had undiagnosed leg pain, with secondary stomach pain. Fatigue, occasional headache. The pain has been starting at the bottom of feet, migrating over few days upward, to stop at lower back. Walking is painful. she's worse in the morning. This will last from 12-30 days. She'll have 12 or so good days, then sick again. She has missed 7 weeks of school this year. (7 last year too)
She tested positive for Lyme 12/06. Treated with massive amounts of antibiotics. Main complaint w/ lyme was abdonminal, as well as fatigue and sore all over, even sensitive skin. Ceftin seemed to work. Think she's cured of Lyme. This latest bout of illness started 11/07. We've seen very good docs, in CT.
Today-rheumatologist thinks might be peripheral neuropathy. We've seen IDs, pediatrician, neurologists, rheumatologists.
Help! Is it neurological? Tarlov cyst? Parasites? HGA? We need to cure this girl, she's missing out on so much.
Thanks for any input.