I have had lower abdominal pains for the past ten years - at times extremely painful generalised lower abdominal. I am convinced that the cause is parasitic, but impossible to convince doctors - because of, presumably, low incidence of parasitic infection they dont bother looking for it
I did look for it by examining stools. I took an OTC worm treatment regularly for a number of months, 10 years ago, when abdominal pain first started and examined every stool. Of course the OTC medicine was ineffective, but I did find a "fluke" embedded in a stool on one occasion. It was about 2cm long and 1cm at widest, reddish brown, almost translucent. I did put it in a specimen jar, but next day it was totally shrivelled up - so i threy it out.
I mentioned this to the Gastroentrolgist at the time. His comment was that he didnt see any evidence of parasites in the colonoscpy. End of story.
Eventually, about 8 months after the abdominal pains started the Gastroenterologist prescribed a course of 'Flagyl'. The effect of the flagyl was dramatic - it gave me crippling lower abdominal pains after a coouple of days of starting the course of flagyl. I phoned the Gastroenterologist and told him i was cripled with lower abdominal pains. His advice was to me was to stop taking the flagyl for a day, then restart the flagyl -which i did. He was right. The abdominal pains went away after a day and did not return when i restarted taking the flagyl a couple of days later.
His explanation to be was that i must have had a bacterial infection. The abdominal pains were being caused by the bacteria releasing a toxin, and when the bacteria were killed by the flagyl they again released the toxin - causing the severe abdominal pains. The local GP called this a "Herxheimer" reaction (and no I dont have syphilis).
(I am now convinced - for reason i will explain later - that the flagyl was not killing bacteria, but was killing parasites - accidently, of course, collateral damage, - as flagyl is not an anti parasitic drug - although I am sure the FDA does not test flagyl to make sure it is safe for parasites. Why would they?).
The flagyl did stop the severe generalised abdominal pains (although other lower abdominal pains continued for the past 10 years), at least until last year when I had another severe attack of the same severe generalised abdominal pain. I immediately went to a GP (my GP of ten years ago had retired, and my medical files lost/destroyed) and got another course of flagyl. The reaction to the flagyl this time was entirely different.
Ten years ago when this first started, I also appeared to have a nephritis, which arose same time as the severe lower inestinal pains. I was convinced then that the nephritis and the abdominal pains were symptoms of the same cause agent - but this was not the doctors view. They treated both symptoms separately. The kidney specialist said that the the nephritis, in my case, was being caused by an auto immune response to some virus or other, which the specialist tried to identify through lots of pathology tests.
I have since read recently that some parasites can indeed provoke an immune response in the human body.