Swelling in right side of lower belly

I'm having some swelling in the lower right side of my belly. I'm 18 weeks so that's around the area where the baby is at the moment and it's only swollen on the right side. I did have some rough pain last night after having sex with my SO, he decided he wanted to be a little more rough and it was fun but after there was a lot of pain and now I wake up with swelling in my lower belly where the pain was, all on the right side of my lower belly! Any idea what this is or if it's normal!