Are these contractions??

I'm 37 weeks, my husband and I had sex tonight then maybe 15 mins later I started getting strong pains in my lower abdomen, it feels like bad period cramps, I could barely sit or stand straight, laying isnt much better.

They are coming in waves it seems, I'll be perfectly ok and then the strong cramps will come back for maybe 30-45 seconds. Normally I do cramp after sex but itll be a continuous dull ache for about an hour, I've never had them come and go like this. I'm a FTM and don't really know what to expect😥