Hello, I would be happy to help you with your question.
Given that you are 30 weeks pregnant, and given the level and duration of pain that you are experiencing, this absolutely needs to be brought to the attention of your OB/GYN immediately. You need to be checked for contractions and an ultrasound
of the placenta might even be indicated to check for bleeding. While this might represent stomach related problems or reflux symptoms, this needs to be evaluated as soon as possible.
I hope that this helps. Good luck and thank you for visiting.