Hi there, I'm a newbie too!

Firstly I think we should make the distinction that the reason your shoulder was in pain in your dream was because of the way you were sleeping. At least that's what it sounds like. Your dream didn't make your shoulder hurt.
I've had similar experiences. Sometimes I sleep with my hand/wrist in a really stupid position that puts a lot of pressure on the joint and can limit blood flow to the hand. I've had dreams in which my hand hurt and woken up to find my hand swollen due to the decreased circulation.

Secondly — and maybe I'm not all that qualified to answer this because I've not had a full Lucid Dream yet either — I've heard there's a difference between dream you being able to control the dream and you really being able to control the dream. The later is true lucidity while the former is a dream where you have special powers. I would imagine, if one was honest with oneself, one would know which was the case.