Severe rls, have used everything ropinoral gabapentin etc and nothing but opiates work. could it be something else?

Not impossible: Secondary RLS is caused by or at least associated with another condition eg neuropathy, sleep apnea, severe anemia etc. Primary RLS is RLS with no apparent underlying cause. Your doc should already have ruled out causes of secondary; if not, discuss. There are occasional patients who have such severe RLS that opiates must be resorted to. I've had a couple. It does happen.

Magnesium: No matter what the cause of your restless legs syndrome, increasing your intake of magnesium should help o a signifcant degree. Magnesium helps to calm the function of your entire nervous system. So whether you have a primary magnesium deficiency or some other cause of your RLS, treatment with magnesium should bring relief to some degree.