Jonley,
My wife has a simalar problem, she has what is known as RSD, this is not well known by alot of docotrs but their are a few pain clinics that do specialize around the country (best to resuerch on web). We have had the same issue with the pain and Cymbalta and it interfering greatly with orgasms. We have been told to switch from Cymbalta to Welbuturol(spelling?). We are on year 3 of chronic pain and treatment. I hope this is helpful.
Randy and D