Belly knot :/

Dominique ā€¢ 25yr old Momma of 2! Boy 7šŸ’™& Girl 1yr šŸ’œ

Got up too fast and felt like a stomach knot or cramp but it went away and it made my belly jolt up.. What can it be? I was scared and it hurt. Iā€™m 20 weeks pregnant.