Contractions began, kept me up overnight, and now poof - they've gone!

I'm 38+2. Had a cervix check Thurs, morning, measured 40w, OB sent me for an ultrasound yesterday to see if it's a big full term Baby or a lot of fluid. Baby measured 86th percentile yesterday. I started to notice contractions, different from the BH I'd been having, before I went to bed last night. I had back pressure, low abdominal tightness/ cramps, with whole stomach tightening that was sharp enough to keep me awake though more uncomfortable than painful. Irregular pattern. I kept going from bed to bathroom hoping to at least pass gas or something to no luck. Pink tinged discharge over the last 1.5days too. Drank water and did catch about a 3hr stretch of sleep early this morning. Haven't felt anything now since about 10:15am and it's now 1pm.