Oh, don't give up hope-these things really can ease up. I've had a lot of spasms below my shoulder blades, even in my deltoid muscle below my shoulder, usually induced by too vigorous a workout (although it didn't seem so at the time... gotta learn to pace yourself and ease up to the next level-it takes longer with us). Once it took what seemed like 4 months before my right shoulder could lift that 3 lb weight again (front and side raises-I promoted myself to 5 and 8lbs too quickly-3 seemed too easy after 2 years). But it eventually got better-it really did.

So I've decided to stick with that 3 pounder, no matter how easy it seems-sometimes I'll increase the reps.
I know how awful shoulder pain can be-I've suffered with it too. Best to let things take their course.
I can also relate to the sciatic problem. We have 2 cardio machines at the gym-elliptical (oval motion) and cross-trainer (circular motion). Seemed I would always get off the elliptical limping, so the gym owner suggested I try the other-which I've stuck with. I'm pretty stubborn, so on occasion I've gotten on while sciatic flaring, only to dismount feeling better, and sometimes I've gotten on fine, and gotten off limping. It's really unpredictable. If I'm in a nasty flare, I skip the gym altogether.
BTW, for your shoulder, have you tried calcium and magnesium supplementation? If I do spasm these days, I will take my flexeril and deal with the drowsiness...