Aw, that sounds uncomfortable, mama! Abdominal pain during pregnancy can happen for a few reasons, but since you're already on isoxilan from your OB, I'd really suggest going back to her if the pain hasn't improved or keeps coming back, sometimes it needs a different approach or she might want to check you in person to make sure everything's okay. A few of my mum friends experienced similar cramping around that time and one of them had to switch medications because the first one wasn't working for her, so don't hesitate to follow up with your doctor agad agad.