Severe Pain In Left Arm

For 5 days now i've been having a throbbing tingling sharp kind of pain in my left arm. Its mainly felt in the deltoid, round the elbow, forearm and slightly in the wrist and occasionally in the thumb and pointer finger. My neck has also been fairly stiff and a bit saw also. I went to the doctors today but while i was there i wasn't in pain as it is on and off most of the time its painful and occasionally its not as painful. Due to there being no pain during the time i was at the doctors i don't think he as able to give an accurate diagnosis. He said its tennis elbow and that the deltoid pain was something to do with the shoulder bursa. i'm not convinced by this though as the pain is the same through out the entire arm and does not seem to be seperate problems. Tennis elbow could be true but the pain is there constantly (other than the times where pain isn't so bad) rather than there when i bend my palm backwards and do movements which cause pain due to tennis elbow. I think it possibly could be a nerve form reading articles it seems likely cause the neck is stiff and slightly saw and pain runs down the entire arm and into the thumb and pointer finger. Possibly the ulnar nerve is damaged? If anyone knows what it could be that would be much appreciated and any way of treating it. Thank you.