What is this feeling ?

I'm 27 weeks tomorrow , yesterday and today I've had the strangest feeling in my tummy , it's kind of like when you're really nervous or anxious about something and it makes you need to poop , I'm a little nervous about this feeling as I had it before I went into preterm labour with my daughter at 29 week's, I haven't had any loss of water or mucous or any contractions, the baby is sideways and has been quite active today , it's just a strange feeling , anyone else have it ? what could it be ? xx