I feel kind of stupid even asking but...

For the past few days I’ve been having period-like cramps throughout the day. I don’t think they’re contractions or Braxton Hicks because they last for hours at a time instead of coming and going.

Sometimes I get cramps and it turns out to be gas, but these are different. They last awhile and eventually go away. Anyone know what this could be? I was assuming it’s just a normal part of the end of pregnancy (I’m 39w1d) but I now I’m not sure.