I have pain in my upper forearm. it hurts when i extend my arm. nerves are more tense to the touch than other arm. i think it is my veins or nerves. ?

Check it out: If no response to heat or ice or OTC treatments you may want to see your doc. Could be nerves or musculoskeletal . If doc can't help chiropractor may be helpful.

You need emg/ncs: You have a nerve problem and you need an electro diagnostic study to determine a diagnosis

Upper forearm pain: Pain which changes with position usually is related to muscle pain. The extensor muscles of the forearm, extensor carpi ulnaris, and radialis may be involved. The nerves that enervate these muscles, the ulnar and radial nerves will be more sensitive in certain positions. Usually veins and arteries don't cause pain unless the blood suppy to them is cut off. Seek medical attention for this.