What are these pains?

Ok so for the past 2 nights I've been getting these pains and I'm scared it may be early labor idk? I suddenly just get pain in my lower abdomen that wraps all the way to my back. I thought maybe contractions but it's not a pattern and it doesn't come and go. It's just a constant pain that lasts for like 5 minutes then goes and doesn't come back. It happened last night and just now to where it woke me up out of my sleep. I'm almost 33 weeks.