Need an answer!!

Im 34w 4d pregnant, I was walking my 6 year old to class while carrying my almost 1 1/2 year old, who’s almost 30 pounds. I got this weird “pop” sensation in my stomach and almost immediately got mild cramps in my lower stomach. Shortly after, maybe 5 mins or so I’m walking back to my car and start getting these really sharp pains all across my stomach and lower stomach and into my lower back. It hurt pretty bad. They pain has simmered down some and doesn’t hurt as bad but it’s still there. I’m just wondering what could this have been? Should I call my doctors? Had this happened to anyone else before???