MaybeChange, dont get caught into CFS crap. POIS is due to nutritional deficiencies that doctors do not recognize. Based on your genetics, your body has a harder time to metabolize certain nutrients, and added to whamy is when that particular incoming nutrient is already reduced in your diet, and further added to the whamy is when you supplement it in the wrong form. Case in point, Folate / Folic / Methyl Folate / Folinic. There are many other examples. Unfortunately, the solution of POIS lies in your ability to garner research, understand your body, and then carefully experiment, or take guidance of a real knowledgeable practitioner.
I have miserably suffered from POIS for 3 decades. And now I have a e (ejaculation) 3 times daily and in fact I feel better after it then before it. I miserably toiled here on this forum, trying to find answers, but I couldn't find it all. I would advice is to use this forum (and use google) for understanding medical profession itself. You'd be suprised how much doctors dont know yet, how much researchers dont know yet. Your knowledge will soon equal theirs, and thats I guarantee you, at that time you will absolutely conquer POIS.