First of all, you should avoid antihistamines like Benadryl (Diphenhydramine) and Doxylamine (Unisom, others) as they can really exacerbate akathisia and restless legs syndrome. If you find that they do not have this effect on you, they can be a very valuable OTC sedative/sleep aid.
In my experience, Marijuana helps to relax me and get to sleep. For others though, they can just make their withdrawal worse both physically and psychologically.
Taking a hot shower or bath right before you go to sleep can also be helpful.
If you're willing to consult a physician regarding your difficulties, they will probably write you a prescription for Clonidine or even a benzo if you're lucky. Clonidine is a sort of gold standard of treatment for those in w/d. It's a powerful sedative and will greatly reduce the feelings of inner restlessness that you are probably experiencing. It can also be helpful in reducing anxiety.
Hope this helps