Okay got a question for those over 18 weeks... I have been feeling really great lately, the past 2…

Okay got a question for those over 18 weeks... I have been feeling really great lately, the past 2 days all of a sudden my body has been hurting SO bad! My pelvic bones just ache, my SI joint is screaming and when I walk my SI joints pop... I know eventually I'd get to this point again... but it was literally one day I was good, the next I was not! Also last night the top of my uterus was SO hard, like a never ending cramp, and my sides were aching... I did walk up and down the hills surrounding my apartment looking for my cat... but it's nothing out of the ordinary for me... any thoughts or suggestions? I'm increasing my water and drinking a Gatorade to see if that does anything... I just can't believe how quickly my body changed!!