what do contractions feel like?

So last night I had sex as well as did lotssss of walking and I felt fine after that. But then early this morning while waking up for work I felt two STRONG cramps and thought they were contractions but I didn’t feel my upper stomach tightening? The cramps were done below closer to my waist. I’ve been very cranky the cramps come and go now but i can’t time them because they only last a couple seconds or so? early labor? or just a messed up stomach lol

** update **

Went to the doctor this morning and got my membranes sweepd.. Im almost a 4 and 75% effaced. My doctor said she would be surprised if I didn’t go into labor tonight!