Sharp pain!

Out of know where i got this sharp ass pain on the left side of the uterus went up to my tummy, and down to the left side of my vagina and the left side of lower back hurts a little i am 17 weeks and 2'days. Could this be ligament pains? I feel a knot on the left side so i pretty sure that is where the baby is. I also can barley sit up without getting  the left side shar pain, bit if i sit still its fine.