Cramps at 19 weeks

I’m having low, aching, menstrual like cramps. At first It just happened twice over Christmas, first thing in the morning. I drank a lot of water and it went away in 45 minutes or so. This weekend it came back, it seems to start more when I’m standing up and moving around, water isn’t helping, and while it does go away after a bit it then comes back a little stronger. Is this round ligament pain? I’ve had other, sharp pains on one side or the other triggered by sudden movements, but that’s not what this feels like. No blood or discharge, but some backache and pressure.