a long question about left side neck/shoulder/arm pain...?

hi;

for the past 2 months or so i've had pain in my left shoulder up thru the neck and down to the arm. it hurts to just pick up an empty cup with my left hand or turn my head left let alone anything else. advil, motrin, excedrin back and body, nothing works. it does feel a bit better when the hot water from the shower is running over it. i've even tried putting icy hot on it, no difference.

now, for the past 2 weeks i've been selling plazma 2X a week. once last week and once last night, both at least 10hrs after i gave plazma the same day, both my lower legs, thighs, etc cramped so bad i could hardly walk...woke me from a good sleep. it was like they were trying to "lock up". u wanna discuss pain. took at least 20 minutes to feel better...BUT during that time i did notice one thing...no left side shoulder/neck/arm/hand pain..i know this because i was gripping the bathroom counter so hard with both hands just to stay upright, tossing my head and neck back and forth writhing in pain from the cramping, and no pain there at all.

now i know when u lose fluids quickly like having the plazma pumped out that sometimes cramping can occur because of the loss of saline, even tho they are pumping a small amount of saline back into me after removing the plazma.

i've thought about a charlie horse for the leg cramping, i've also thought about tennis elbow or tendonitus for the left side pain...i've even thought of a small stroke that just affected the left side but there's no facial problems, etc...just a continious twisting pulling pain from the neck thru to the hand...any other thoughts?

a sample of the plazma is checked each time and they are having no problems with that at all.

i'm 47, never did drugs, don't drink or smoke and do physical labor 10hrs a day at work.

right side no problems at all.

thank you.