What Causes Severe Pain In Thighs And Legs?

My mother has Vaath (Waath, dont know what u call this in English)? Daily pain in her thighs and legs and makes it difficult to walk. She takes some powder prescribed by GP supposed to be ayurvedic. She gets immediate relief and she takes it every day. But some doctors told me that it may contain steriods and it has severe side effects. I would like to know if there are any medicines or treatment for such patients?