I'm 39 weeks pregnant. And having BAD contractions at night. The subside in the morning, but never go away.

I have been having terrible contractions at night that wake me up for the past 4 nights now. They aren't very consistant, sometimes 15 minutes apart, sometimes 5 minutes, sometimes 20 minutes, and sometimes when I just move a certain way. They subside in the morning and are less painful, still not consistant. This is my 3rd pregnancy, I had back labor with the first, and the second was born 12 hours after contractions started so this doesn't seem normal to me. I also have alot of pressure on my rectum, and in my pelvis area. Should I call my doctor or just wait for the contractions to become more regular?