17 weeks with pain, please help!?

So I am 17 1/2 weeks, I was sitting down noticed light pain across the front of my adominal area. I moved sat somewhere else. Still something. Decided to go lay down and by the time I got there to lay down, I was bent over in soooo much pain. The pain had moved to my low back as well. It was painful enough I was crying, it only lasted for a solid 10 minutes. The day before about the same time I had an ultrasound to get 4-d pictures, and I am wondering if the probing around had effect. Has anyone had this this early on, PLEASE help! I see my regular doctor in 2 weeks so I will ask him then. p.s. haven't had problems since