There is a connection between giardia that one often gets in third world countries and hypothyroidism and auto-immune diseases

So, if when you were young you were an international traveler and you drank water or ate food grown in third world countries often fertilized with human waste then it is also possible that you got giardia whether you had the classic symptoms or not which are similar to Montezuma's revenge in Mexico or Deli Belly in India. 

For example, I got giardia from likely Kathmandu, Nepal because most roads were not paved then around Kathmandu in 1985 and 1986 when I was there with my family. So, the feces particles in the dust from the primitive nature of how things were done then is likely how I and most of my family got giardia then. As a direct result I likely got Hypothyrodism in my 40s but wasn't diagnosed until I was around 58 years old in 2006. Then I visited an American Nurse practitioner here in the U.S. who told me that giardia from Asia is often associated with Hypothyroidism or Auto-immune diseases too. At this point one of my children now 50 has an auto-immune disease which is not fatal but does change ones life and another daughter born about 10 years after the family was in Asia for 4 months also has an auto-immune disease associated with hypothyroidism. So, if you are someone like me who traveled at lot until you were in your 40s or after you might want to take a T3 and T4 blood test to see at the very least whether you have hypothyroidism from giardia like I presently do. I take Armour Thyroid even though insurance doesn't pay for it because it is like being 20 years old again in my mind when I take this medicine. Before I was diagnosed with hypothyroidism in 2006 when I was 58 I expected to die by 60 or 65 likely from bronchitis or pneumonia. When I began taking Armour Thyroid my life was extended because I no longer got bronchitis all the time and I no longer had to take Sudafed to survive these boughts sometimes for 3 or more weeks subscribed to by the doctor which after about a week or two start to make you hallucinate which I really don't like. I like to be in control of my reality and not goofy like that.

So, the point is that if you are not feeling right since having giardia from a third world nation or even got it here in the U.S. you might want to take a T3 and a T4 blood test which will diagnose hypothyroidism.