My mothers friend had been having joint and muscle pain all over her body and pelvic cramping?

This has been going on for several years now and the doctor does not know how to treat it.She is about to reach menopause. she's now 49 years old. she takes calcium+ magnesium and vitimin D. She eats healthy inclidinf fruits and vegetables no sugar less bread, some meat. She walks everyday and tries to strectch her muscles, but the cramping is worst when she excercises. Some days she can't move because the pain is so bad. Some months it's better when she knows she is about to have a period then all the pain disappears for a short time. Any advice?