First thing to be sure you check is his iron levels. Doctor's should have ordered a blood panel already and checked this, if not get it done soon. Iron supplements may be needed for a few months if his iron is very low. It doesn't seem to come up quickly, so if it is low the iron supplements as well as medication. My son was on Gabapentin for awhile as well to raise the iron levels. This medication also has a drowsiness side effect, so could help your son with sleep. Once my son started the iron and medication, the RLS went away in about 4-6 weeks and has stayed gone. Hope he get's better soon!