Wow! Yes I have had the exact same symptoms since I was very little. It was worse and more frequent when I was younger but I still get those doubled over in pain cramps for a couple of minutes at least once a month. I don't know what causes it but I am having a really bad episode right now. I got very sick 3 nights ago with intense nausea and vomiting. I had vomiting episodes every 10-20 minutes for 5 hours. My husband ended up taking me to the ER - they thought it was food poisoning, but this was before the intense cramping. Also - all they did were blood tests, which obviously give a baseline for somethings but is not good for diagnosing everything. Of course, there was nothing left after the first few episodes and all I was throwing up was a white foamy substance. I am now having severe constipation and very bad cramps. I have taken 6 Correctol tablets since the night of the vomiting and I had no luck. I have take 2 glycerin suppositories and finally, my intestines have been able to work the bowl movements out. I took the 2nd one after an intensely painful cramping episode woke me up from sleep tonight. It was very painful and I am worried. The pain went away for a while after I went to the bathroom with the first suppository and I though that was the end of it. Hopefully, this will be the tail end of it.
Do you know what might be causing it?

Hmm...that's very interesting. Yours sounds a lot more serious than mine. It sounds like an actual disease with the vomiting and the diarrhea and such. I'm beginning to think maybe I was just constipated...

The bad cramps I've had were never accompanied by any other symptoms and I've never seen a doctor for and I've never told a doctor about it.

Has a doctor ever been able to guess what's been going on? Have you told one recently about your symptoms?

I have intense abdominal pain too. I sit on the toilet clenching my stomach and almost crying because of the pain. The pain lasts for 10 seconds at a time every 5-10 min or so. The whole episode lasts about 30-60 minutes. I massage my stomach and intestines and wait to hear the slush move around in my stomach. Immediately after I hear a bubble burst inside my stomach, the flood gates open. Relief. This sounds very disgusting, but it's just the truth. I believe it's build up of excess gas that's causing the sharp pain.