The onset has little pattern to it, but often does occur after a long day of vigorous exercise like skiing or hiking. It seems to have absolutely nothing to do with my diet. It often hits me while I am taking a deep breath, or "stretching tall." The most common way to trigger it is during urination - it feels like the bladder is contracting and pulling at the nerve or length of intestine.
When I was 16, I was diagnosed with umbilical hernia and I had surgery for it. The pain recurred afterwards but had changed in character significantly.
I have seen many doctors over the years, and they are consistently stumped, and usually blow me off as "having gas," or occasionally I will be accused of drug-seeking. I do believe doctors to be completely worthless at this point with respect to my condition.
Anyway, it seems as though this may be related to adhesions formed during the hernia surgery. I will probably not investigate surgery at this point, as the full-blown episodes have become far enough apart that I don't feel as crippled as I once did. But I would like to hear from others who have had similar symptoms, if you are out there. I have been searching for answers for 20 years and this feels like the closest I have come.
Thanks for listening, Bob