What does Braxton hicks feels like

I am 33 weeks and 2 days with B/G twins. I had an ultrasound on Monday and everything was fine. They are both head down. The girl is farther down. I woke up tonight with my left side hurting a lot. It hurts when he kicks my ribs but this hurt more than normal and lasted for awhile, maybe 40 mins or so. It stopped after getting out of bed for a few mins. Now I can tell they are both awake. I am not sure if what I felt were contractions or him up by my ribs.