Help!

I am 35 weeks pregnant and a FTM. Yesterday I was in a very minor RTA (car crash) and went to the hospital to get checked out. The midwives said everything is fine and had NST done. Told to go home and relax. I've woken up today with nausea, diarrhoea (had regularly throughout pregnancy but not this severe) and several tightenings. Are these normal symptoms for this later stage or should I be more concerned?

Yesterday on the NST the monitor was showing regular tightenings but the midwife said I had an irritable uterus.

What should I do?