Suggest Treatment For Severe Pain In The Right Leg

my wife has a high level of pain when moving all extremites except her right leg. She can only lay in bed on her back. If she turns to either side she has too much pain to sleep. This has been an ongoing problem for at least a year at different levels of pain. Today it s worse than ever. At previous times we go into the walk in clinic and they take ex-rays but don t find a definate cause. They usually give her some mussle relaxing medication, she goes home and 3 or 4 days later it starts to feel better. She tolerates for aweek or two and it starts over. We wonder how to get this ongoing problem diagnosed?