Unrelated tests ?

I was wondering : as anybody has been tested for EVERYTHING ? I mean by that, any possible medical test imaginable for science, even those really unrelated, that - intuitively - could not cause our symptoms ? As anybody had enough time and money to do that ?

I mean, isn’t it the path to discover the missing link ?

This is not feasible unless you yourself are a doctor and can order every test imaginable on yourself.