Abdominal pain help

Holly • 🌼 mum to Penelope 🧡 baby boy due March 23

Hi everyone, yesterday morning I had on and off mild cramping quite low down. I was first worried that it was a UTI so I drunk lots of water. The cramps were on and off and mainly when I moved so I thought maybe it’s just round ligament pain. Then by the evening when I was in bed the cramp was constant and a lot more painful.. not unbearable but very much like bad period cramps. I woke up around 3am and the cramps hadn’t got any better but when I woke up this morning they were completely gone. I had no bleeding or change in discharge so I have no idea what this was? Also my belly looked slightly different, usually my belly button really sticks out which it wasn’t (still isn’t as much). I almost feel like my belly looks smaller. I’m still feeling baby move which is good but does anyone know what this could be? And if I should let someone know? I’m 29 weeks and just slightly worried because I’ve not experienced any cramping like this during my pregnancy and it lasted the whole day on and off. I stupidly googled and read about placenta separation and got really scared!

Thank you for reading!!