Side of back cramps!

So all day I on off had a bit of an upset stomach/diarrhea. Nothing too bad. I just had to go more than usual. But now I am in the bath and I had to go poop, and I went. It was a Normal poo lol. Not diarrhea. And I just have the worst side of the back cramps on the left side mostly! At first I thought the baby was kicking somewhere inside but now it just still cramps. Should I be concerned? Can’t tell if it’s from upset tummy off and on today or if it’s something else? Can u get back cramps from Braxton Hicks? Never could tell if I even had bh before! I am 37 weeks tomorrow!