Question
i work @ re bottle @ can redemption center and throw 15,000-30,000 soda /beer cans and or plastic bottles a day in all different directions 6 days a week and while carrying 480 per bag with my left hand in front straight out in front and manuvering around corners i would some times feel a burning sensation in my lower deltiod now when i am working the pain gets so bad on bussy days that there is a feeling like i have a IV> needle in my elbow pit and if i move just rite just rite it is like  sharp object is being shoved rite thru my upper arm from the outside  the pain is there all the time and i can not sleep ion my left side or raise my left arm above my head to place it under my pillow @ nite and somnights it wakes me up out of a dead sleep cussing and swearing it hurts so bad and my hand goes numb when i sleep andso when i wake up in the night and morning it is all tinglely and burning as well it falls asleep when i drive  a rehab dr @ the v.a.hospital said i have week shoulders at that point i felt it usless to tell him what i doo all day as i didnt feel he cared anyhow it is killin me rite now typing this to you

Answer
you know it sounds like an injury a chiropractor will really get his/her hands on and help you,  or even a physical therapist would help. if it doesn't improve in 4-6 weeks then get an mri. i would not be working like that either.
vets have access to chiropractic , you must ask your VA doctor for a referral.