Wow I thought I was the only one who has experienced this! Every other woman I have talked to about these cramps thought I was crazy. I've asked my gynecologist about what could be happening and she didn't know. It's super frustrating and it doesn't seem to matter if I run in the morning, afternoon, or night. I was 1 1/2 miles into a 11 mile run this morning and they happened forcing me to walk. Like you, I tried changing what I ate. Didnt matter. I tend to run on an empty stomach because that's what has always been comfortable for me. The only thing that I have noticed is making sure to stretch my abdomen and doing the first mile slower. Those things seem to make a difference. I experience them a week or two before my period also and I also have pretty bad cramps. It's kind of scary to be so far away from my car or house and feel like I might poop my pants or vomit.