Hey Fren, send her to an immunologist for testing - they may be able to help curb the strange illnesses. Also, there are clinics in Mexico or Denver that use your own stem cells to reverse MS. Very expensive but has an 80% cure rate. I have a friend with MS who is currently on a program ( I think it's hemoglobin infusion therapy) through her immunologist that has helped considerably with her overall well-being. It's not a cure, but it helps.
Until then, prayers for your sis…and family.