Can anyone help???????

I’m having this strange sensation. Below knicker line. Been happening for a few days now but it’s not 247. The closest I can describe the feeling is as if I’ve got a little golf ball/bulge feeling in my lower stomach and it occasionally “rolls” every now and then but it doesn’t hurt. I can’t feel it when I lay my hands there because soon as I feel it happen and go to lay my hands there it stops. What could it be? It happens through the day and sometimes at night when I’m laid on my right side. Then sometimes in the middle almost feels like a spasm/pulsing sensation again below knicker line. This is the furthest I’ve got in pregnancy! Is it wind? Or things stretching? It doesn’t hurt when this happens just feels a little odd. I’m 19 wks 2d! Or is this something I should be worried about ??? x