It sounds like you don’t have sufficient control over your situation to use such simple analytical methods.
In complex situations, one has to use statistical analysis to merely reduce the number of variables involved to the point wherein one can use simpler logic. When dealing with health issues, one must go to extreme methods to minimize the number of variables so as to get a reasonably significant statistical data base before analysis can even begin. And usually by the time one has gathered sufficient data, the outside environment has changed in so many ways even such extremes might not be enough. Perhaps they were using a new pesticide that year, a new chemical in the air that altered your physiology such that your P would finish a formula that leads to Q. But a few months later, or with the addition of a different water source, the whole problem goes away.
Many years ago, in a far, far away land, I went to such extremes; “only rice and water for 3 weeks”, then added “one variable at a time” so as to test the effects of that one under those conditions. And of course, did the on and off thing with days in between at least 3 times so as to produce reasonably reliable results - under those conditions in that land at that time with my body in the condition it was in at that time. A few years later would have produced different results. As it was, I tested about 30 different herbs and foods against that backdrop.
In a more chaotic environment even that wouldn’t have worked to tell me anything useful. Simplification is the key along with an awareness that there are far more things changing around you in far more insidious ways than you really want to believe. Every change you make has a far greater probability of causing more trouble than curing any trouble. Your body learns to deal with almost anything consistent. If you keep changing things or others change them for you, neither your mind nor body can properly cope. You become entirely and insidiously dependent upon those doing the changing (the whole point in such changing).
In order to keep up with the changes that you cannot control, your body must be given the right to adapt without your oppressing presumptions. You must allow your sources to slightly vary in directions so that your body can then sense which directions seem to often lead to what condition. But those changes must be subtle and repeated very often without your conscious interference with the subconscious assessment. It takes a lot of time and patience. You must all but forget about it and just go on with life. Gradually, very gradually, the conscious mind becomes aware of a direction that seems reliably good or bad. Some things the body can and will adapt to on its own if given time. But slight swaying is what gives statistical data to the subconscious and allows such learning. The process never really stops until your environment stops changing (no time soon, I would imagine).
Life is about the dance, not the destination.