I keep getting left arm pain between shoulder and elbow. i have osteoarthritis in the neck. is that why?

Possibly: You could have an arthritic bone spur pushing on a nerve causing pain in that area. The other cause that is common is to have a rotator cuff problem in your shoulder that can often cause a referred pain in that area. A detailed exam can usually determine the cause, don't hesitate to be seen.

Possible: yes it's possible that is your arthritis but see a doctor to rule out a cardiac origin of this pain.