Hey, I'm not an expert by any means, but I had a similar experience. My freshman year of college I contracted mono 1st semester and tried to run through it. Bad idea, I started drinking coffee copiously, and beat myself even further into the ground, digging a pretty deep hole. This combined with rigorous academics, and some weekly alcohol overindulgence left me with a severe brand of CFS for almost 2 years. I consistently had a temperature in the low 97's (although this runs in my family). I never got that amount of blood work done, but my Iron was fine and my mononucleosis cleared up approximately 2-3 months after first symptoms. Should note: your times are faster than mine were, but I was mid 15's in the 5k, probably 1:55 800m (never got a chance to race it cause I got sick). At the time of my illness I had also strung together a solid 18 months of training for the first time in my life.
I took some time off after the mono and tried getting back into running but had no luck as every time I'd come back I was fighting some serious lethargy/malaise if not the first day back within a few. I have no way of knowing, but I generally assume that I had some form of adrenal fatigue.
What finally allowed me to come back was taking time off, (still went for long walks when I felt up to it), quitting alcohol and quitting coffee. Also I made a point of getting to bed early and eating no processed garbage food when possible. I'm sure most people will take issue with it, but I really think that quitting coffee was the number one most important aspect of my recovery. I should note that I've always been hypersensitive to caffeine and always disliked the effect prior to getting mono. There is something to be said about a sober night's sleep started before 10pm with a full belly of real food. Not trying to minimize your condition at all, I feel for you, I remember how much my CFS sucked. Stay optimistic! Oh and if you have low T... don't masturbate.