What would you do?

Kat
Lying awake in bed with cramps/BH or actual beginning contractions, I'm unsure. I don't know if the pain is enough to keep me awake or just the idea of it all. I want to go to sleep, because if it's nothing, I want to be at work tomorrow! Also, if it is the start of something, I want to get some rest. Earlier this evening I had a horrible poo (sorry TMI) but it was the kind where your body is just pushing and pushing to clear you out. After that, felt fine and watched tv. Now I'm having almost constant period cramps that are getting worse at times and sporadic tightening. Should I get up and move around, or just lay in bed and try to rest? I don't know what to do here. If it's not labor and I don't get any sleep, I feel sorry for my students tomorrow! I am 38 weeks!