I have that too my Dr said it was uterine irritability, getting things ready to dilate and thin for labor
could be early labour, or it could be silimar to constipation pain... go to the hospital, they should see if you are having contractions, and then they'll do something about it
id call youur doctor,
a few weeeks ago i had the same thing && i had too get my labor stopped id make sure because 33 wks is way too early too welcome a baby in the world.(:::
goood luck mommma, not much longer.