Preterm labor/contractions?

Can anyone explain what it feels like to go into preterm labor? I’m 22 weeks and I woke up in the middle of the night to bad pain radiating in my back and down near my pelvic bone. It wasn’t constant, they were happening about every 4-5 minutes and lasting around 45 seconds. I started drinking a load of water because I thought maybe I was dehydrated but it didn’t help. This is my first so idk what contractions really feel like. Currently having them still, but more erratically.