Hi, I Am Experiencing Pain In My Right Calf. It

Hi, I am experiencing pain in my right calf. It started 4 months ago but it would come and go, now it is constant with a sharp stabbing throbbing pain, the pain hurts badly when I sit and stand, its even worst when I walk. when I lye down it stops but it seems that I have to bend it back just a little to stop it from hurting so much. Can someone " Please" tell me what's wrong with my leg. All the pain starts in my calf behind the knee and then the ankles and feet hurts along with ankle and feet swelling badly. I am diabetic and have just developed high blood pressure problems as well as diabetic neuropathy one year ago.