should I be worried?

I'm 32 weeks +3 ( measuring 2 weeks ahead) since last night I've had absolutely awful back pain barely slept at all.. I've taken paracetamol and that's not seemed to do anything.. my legs feel like jelly I've just got changed and lifted my leg up and felt a really sharp shooting pain in my pelvis almost like I'd trapped his head, I've not really had any tightenings in my belly but it does keep going very hard but nothing painful. I did go to the hospital 2 weeks ago as I thought my waters were leaking but they said they wasn't. The pain in my back is making me feel physically sick and I do have quite a high pain threshold but this is horrendous. Could this be a sign of slow labour? I've not had a show but have had a awful lot more discharge than normal recently.. any advice welcome thanks