Yea I have been having this 30weeks.I agree better be safe and mention it to ur doc. Try to kick ur feet up & fight gravity. Stay hydrated.
I read that for some women braxton hicks could feel like menstrual cramps. I would tell the doctor even if it was something normal.
Get it checked just to rule out any preterm labor stuff... drink a lot of water and see if it still persists. I had this happen last week and I was having contractions and I didnt even know. I too am 33 wks.