Not painful but regular contractions?

This is my first pregnancy...I've been having horrible and regular lower back pain for two days but no stomach pains until this morning. I'm very sure they're contractions but they aren't super painful..I started timing them with an app and the app said I should go to the hospital but should I? The only horrible pain I get is in my lower back. Should I time those too? I'm 39w 2d..