I've seen it a lot - basically from over training, so that is different than Epstein-Barr. Often the Dr does not deal with folks that work out a lot. Still a good idea to validate it is not a virus, or there is not some bone marrow thing.
Lots of things to ask if it is NOT a virus, or real blood/bone thing.
-How much do you train/workout and what?
-Blood test results - Is hematocrit OK, did they test that?
-Diet - Vegan or hi carb?
-How much sleep a night?
-Got a pulse Oximeter? ($20) - what is your SPO2?
-What is your blood pressure? Standing/sitting?
-What is your morning resting HR.