Uy mama, if you're worried about pain or anything unusual, please go see your OB right away, hindi dapat mag-atubili sa ganitong bagay, lalo na ngayon ka pa lang sa 18 weeks.
A few of us moms here had similar worries during pregnancy, at grabe ang peace of mind talaga kapag na-confirm ng doctor na okay lang ang baby, so please don't hesitate to call or visit your clinic today. Take care of yourself!