Frequent tummy ache during the last few weeks of pregnancy?

Coming to 39 weeks and I’ve been pooping frequently. Not sure whether it’s to clear space for the baby due to its limited movements or that my body is preparing for birth? The tummy ache is so bad I have to go to the toilet 3-6 times a day. Did a checkup and baby movement and heartbeat are all good so no issues there. Anybody experienced this before? I’ve asked the doctor but he couldn’t give me an answer lol