Stomach pain during Pregnancy

About 12months ago I gave birth to a beautiful baby boy. It was a very rough delivery but he mad it her safely. 7 months later I found out I was 2 month pregnant. The pregnancy has been fine until this past week. I am 29 weeks a long and my stomach feels like I have done 100 sit ups 3 times a day. It feels like my stomach muscles are going to give up, like they have been stretched to there limit. Should I be worried? Do I need to call my doctor? I teach dance 2 nights a week is this a sign I need to stop? Is this pain just Brazton Hixses? I need help! I am not sure what I should be doing.
Thank you
Cambria