Im 19wks pregnant. earlier today, while picking up a watermelon, i accidentally hit it against my tummy. i felt mild pains for a while, however it subsided. now i tried doing work on my core, however i fell on my lower back/butt. will baby be okay?

It's all physics: A personal watermelon should not be big enough to do much harm (lacks mass). Even a full-sized melon would have to be moving at some speed to cause damage... but the one's at the grocery store are just sitting there (lacks speed) so Baby is most likely fine. If other symptoms happen, such as contractions or vaginal bleeding, one can call her Ob-Gyn doctor. Falling on one's butt usually is ok too.