Alam ko yan, parang nakakaalarming feeling talaga especially pag first time mo! At 19 weeks, mas likely yan baby movements or ligament stretching (yung round ligament pain na biglang kirot), hindi pa Braxton-Hicks since medyo maaga pa, pero totoo na some moms do feel them earlier, a few of us felt random tightenings na hindi consistent pain. Pero if it's continuous, super painful, or may spotting/bleeding, definitely check with your OB agad na lang para peace of mind mo, kasi better safe than sorry talaga sa pregnancy.