stomach cramps

Help!  I get pretty strong stomach cramps when I nurse.  Sometimes they quit when he's finished, sometimes they keep going for hours. I am 7 weeks pp.  They're not period cramps as they're not in my abdomen, they're definitely stomach cramps.  And I know I'm not pregnant as we haven't BDd in a few months.  Does this happen to anyone else?  Have you found a way to make it stop?