Please Help!

I'm 7 weeks post partum and have been having on and off upper abdominal pain. A pain that feels like I've been punched in the gut, making me extremely nauseas & running back and forth to the bathroom with awful diahhrea. It usually happens late at night & although it's awful pain, I find myself forgetting about it in the mornings. I'm EBF & my girl has been extremely gassy & screams all the time so I assumed I was lactos intolerant, but I've been off of milk & im still in awful pain & she is still crying! Any ideas of what this pain could be!?