Help please

Okay guys, I'm just a little worried. I'm 34 weeks FTM and my stomach has felt soooo heavy all day. For the past 2-3 hours or so I have this pinching sensation or light menstral cramp feeling that keeps coming and going. It only lasts about 3 seconds max and is about every 20/ 30 seconds sometimes a minute apart from each other. It's definitely bearable, but odd. Is this of concern? Or could this be just another "strange and uncomfortable but totally normal 3rd trimester symptom"? PLEASE I don't want to go to the ER but if this could be something of concern I need to know. :-/