Labor or just normal?

I’m 37 weeks. Me & my boyfriend had sex & he ejaculated inside of me. It has been 45 min since we had sex & my lower back has hurt & my stomach keeps getting super hard & feels like I’m on my period. Also, my vagina has been hurting. Is this normal after sex this late in pregnancy or could this be labor? Also.... I’ve been having to pee every few minutes and it’s only a tiny bit each time

UPDATE: it’s been like this for 3 hours now