PLEASE READ, need some help.😕

I was outside riding a bike, not more then 2-3 minutes (just testing it) and I went to lay down because I was out of breath. When I then stood up I got the extremely painful stretching feeling (were the image shows). And I had to lay back down because it was so painful. It didn’t last for more then 1-3 minutes. And it’s no longer as painful just slightly sore. But the pain comes back a little when I use my stomach muscles to get up. What could it be? Could it be round ligament pain? I’m only 5 1/2 weeks but I’ve heard it possibly. Or should I expect the worse and is it a ectopic pregnancy? Should I call on Monday and get an appointment to have it checked out?