A few months ago I got this funny pain in my lower abdomen for about a day, didn't think anything of it ... until it came back a few weeks later, then again a few weeks after that. When I realised it was every 28 days and always on my 14th day I googled it and came up with Mittelschmerz! I had never heard of it and none of my family or friends have experienced/heard of it either. How common/uncommon is it?