Diarrhea: why me?

In one day's time, I went from 50 years of normal BMs to pedal to the metal diarrhea, now in it's 12th straight week.  I had a colonoscopy done about four weeks ago, which showed no problems.  They also gave me a stool sample kit and tested that, and a blood test was done as well.  It was then suggested by the surgeon to have an upper GI done.  I have a problem with that.  Having lived a very athletic lifestyle for all of those 50 years, I have logged much time under an x-ray machine.  Plus, due to an auto accident in '87, resulting in a major head injury, I had full body CAT Scans done and a few done of my head.  So I've been radiated enough, and would prefer not doing the upper GI if I can get away with it.  I have, just for the heck of it, tested myself for lactose intolerance, intolerance to wheat, as well as anything else I could think of.  I am now testing myself for an intolerance to vitamin C, but after two days of that, it appears it isn't vitamin C that's bothering me.  Do you have any suggestions I could consider, or a suggestion as to what type of doctor I should see?      

[boron]

You can have a low-fructose diet trial:
http://www.medhelp.org/user_journals/show/21247?personal_page_id=801

Have they tested your stool for parasites?

Diarrhea is often due to small intestinal disorders like celiac disease (gluten-free diet trial for 1-2 weeks) or Crohn's disease that sometimes affects only small intestine so it wouldn't be seen in colonoscopy. This would require capsule endoscopy. Before that an upper endoscopy will be suggested to you by a gastroenterologist.

4 days low-fructose diet trial, and 1-2 weeks gluten-free diet trial - this is what you can try.

[garygs415]

Thank you for the response.  To answer your question about parasites, the surgeon said that he would see evidence of parasites when he did the colonoscopy, and when he was done, he said he didn't see anything.  Now, as far as celiac disease, wouldn't he have been able to detect that during the colonoscopy?  Because I asked him about that, and I thought he said he'd check for that.    

Back to the parasites, though... my wife and I own a pet boarding facility, and we work with dozens of boarders every day.  Too, we work in greyhound rescue, the local humane society, the New Guinea Singing Dog Conservation Society, American Dingo rescue, so, again, we're around rescue dogs, as well as our own 18 dogs every day.  So I would think parasites would be a real possibility.  Earlier in the spring, we boarded two dogs, Bud and Ellis, who had just been diagnosed with lung worms!  While feeding them one day, leaning over to sit their bowls down, Bud jumped up and licked me right across my mouth!  Argh!    

[boron]

Parasites may be one-cell parasites or worms and they may appear in the colon or small intestine. With a colonoscopy only the colon is checked, beside that, colonoscopy preparation has flushed eventual parasites out.

Celiac disease affects only the small intestine. Even if doctor has checked a last few centimetres of the small intestine during colonoscopy, I'm not sutre if he was able to exclude celiac disease just with that. Biopsy and examination of small intestinal mucosa would be needed and this is usually taken from duodenum - during upper endoscopy.

I would try stool test for parasites first. Test is often false positive so three samples from three bowel movements from different days would be needed in negative test and parasites would be still suspected. Finding elevated IgE antibodies and eosinophils (a type of white blood cells) in the blood would additionaly speak for parasites. Diarrhea in parasites often has a waxy wanning course and is usually not a bad diarrhea but may be prolonged. Some mucus is often also present.

Other possible causes:
- lactose intolerance
- fructose malabsorption
- celiac disease
- Crohn's disease

..so disorders that affect small intestine. Fructose malabsorption and lactose intolerance can be excluded by two simple diet trials:
http://www.medhelp.org/user_journals/index/372821?personal_page_id=801

[garygs415]

I have an appointment with a gastroenterologist next Friday.  Hopefully he can figure out what's going on.  My wife and I have a concert tomorrow night, as well as next Thursday night.  May have to go without eating all day each of those two days to keep from having to make a mad dash to a toilet I'd rather not use!  Concerts - these kind of concerts - aren't known for their clean toilets.  Geez, when are we going to grow up?