I have a long history of digestive problems due to radiation treatments 25 years ago and my symptoms were different in 2018 so I went to Mayo Clinic. The GI doctor there ordered an endoscopy where they drew fluid from my small intestine and sent it to the lab for culture and it came back positive for SIBO. I had to leave to go back home the next day so I didn't get much more info. TBH I don't think they knew as much in 2018 about SIBO as they now know.

I had a urine test called the Organic Acids Test, and my functional medicine doctor ordered it. I'm thinking a stool test might be able to give me more info, though.