What could be causing this abdominal pain?

I gave birth almost exactly 6 months ago vaginally. The delivery was super fast. Literally 1 contraction and 2 pushes. She was out in 2 minutes. Labor went fantastic, but ever since then my abdomen has been tender. I went back for my 12 week post partum check up, she checked my uterus and such, and said everything was back in place, but during all that poking and prodding it really hurt! (It's never hurt before). I didn't say anything, cause I thought it was normal, plus I was making an in pain face, LOL. Anyway, the pain has been persistent through these last months, but not severe. Yesterday it seemed to be worse. I was playing with my daughter(the six month old), and she stood on my abdomen for a minute and it hurt pretty bad. It's also tender during sex. It's not a debilitating pain, but still uncomfortable, none the less. It seemed to feel better after a hot shower too. Anyone have any ideas or experience in this area? My only symptom is pain. No redness, swelling, discharge of any kind, and no smell. Nothing wrong when I pee either. I'm rather confused. Maybe its a pulled muscle from the fast delivery?