Medical student's apparent celiac disease responded to giardiasis treatment

Oh wow, I have the first half of this situation. I went through a period where my digestion was so bad that it was affecting my ability to function from day to day. I didn't get anything useful from my gastro; I even had a negative celiac antibody test. Eventually I started rigorously tracking everything I ate against my symptoms, and after a few months I was able to draw a strong correlation with gluten intake. From memory it was in the 0.7 range. The day I cut out gluten, a set of awful digestive symptoms completely left my life. They return any time I am glutened.

I was fortunate that over time I managed to return myself to full capacity, through reading a ton of research and running dozens of experiments like the above. But it was so damn hard. The symptoms reduced my ability to use my brain to fix myself. And if you're not a careful eater, it's not at all intuitive which foods contain gluten. This was also almost a decade ago while living in a developing country, so it wasn't even apparent that gluten might be a suspect.

I'm currently based in the US - does anyone know how one might get properly tested for chronic giardiasis, as a person who isn't themselves in microbiology? I almost certainly encountered poorly treated water in that period of my life.

Also - I can't help but suspect that a nontrivial percentage of the developing world is living below their full capacity due to something like this. Neglected tropical diseases are a horrendous category.