Does this sound like start of labour? 36 weeks.

Ok. So I've been getting constant menstral cramps so my uterus is contracting. (Not braxton hicks!!!!) constant 12 hours plus. Nothing makes them go, the pressure in my pelvis is increasing, whether babies moved further engaged or what I don't know but my hips and lower back have a constant full ache, feels heavy, my thighs hurt, they feel as if a massive strain is on them. I've had an increase in discharge, not an odd color, lts normal just every now and then a little of yellowy discharge comes out. I was wondering if this was my plug thinning.  Anyway does this sound like the start of something? I'm completely put off by ringing delivery as they made me feel stupid last time. But I know I'm not being paranoid. Thanks!