Understanding your body can be similar. While medical expertise is absolutely worth consulting, doctors can only base their diagnoses on your self-reported symptoms and on their examinations at single points in time. The more data you collect and report to the doctor, the more likely you can work out exactly what's going on.
I know someone who lived with chronic discomfort, observed over several years, and after many doctor visits finally pinpointed the root cause. Best wishes to the author on his search.