When to go to the hospital with contractions

Patient: I am having menstrual like cramps constantly at 38 weeks pregnant. about every ten minutes, i get a sharp pain with pressure and tightening from the front to the back. it hurts, but is not excruciating. also, my legs feel achy. are these contractions and should i be thinking about going to the hospital yet? on thursday i was almost 3 cm dilated and 90% effaced.

Symptoms: Contractions…tightening, pressure, sharp pain radiating from groin to anus.