Early labor or normal pains?? (37 weeks)

For the past 2-3 days I've been having cramps, back pain and my belly tightening that keeps getting worse...last night I thought I was having contractions 15 minutes apart lasting about 30 seconds but when I woke up it just went back to the cramps and back pain and my bump tightening. What should I do? Is this early labor or just normal pains?