Suggest Treatment For Restless Leg Syndrome

HI my boyfriend just had both knees replaced at the same time, he is on ox and trying to stop taking them. he has been on them for about 8 months.. so he went cold turkey but is having restless leg synd. plus withdrawals
,and lack of sleep saying he feels like bugs crawling all over him. was wondering if there is a natural suppliemt the he can take to help