Is this the start of labor?

Sara
I'm a FTM at 39 wks and 1d and took castor oil last night because I'm just so uncomfortable and ready for this LO to be here! I had diarrhea and GI cramping most of the night. Today I'm having pretty painful cramps (no longer GI cramps and diarrhea). If I walk around they feel like a stitch in your side from exercise or really bad period cramps. Also feels like there's more pelvic pressure, pelvis symphysis pain and stretching, lightening crotch when I stand up making me have to waddle. My water hasn't broken. I'm timing the cramps (I don't know if I can call them contractions because I can usually talk through them and they make my tummy tight, but not always ridiculously so) and they're inconsistent--anywhere from 30 seconds to 5 minutes long with 2-20 minutes interval between them. Sometimes they start to have a regular pattern, but then they'll stop. Am I in early labor or false labor that may subside? Should I call my Obgyn at this point?