I'm not surprised at all to hear that your EBV results were high, given the circumstances you've described. To answer one of your questions above, yes, the virus basically remains dormant in one's body for the rest of your life; however, many factors such as high stress or continued over-exertion can cause a "mono" relapse. This is also common in instances where the immune system becomes compromised, either due to internal or external factors. I don't know enough about the heart infection to comment on that, but from what I've heard, EBV relapses can become more severe with age, so it's very possible that the re-activation is causing other health problems. And unfortunately, the best way to get over it is, as you said, to get lots of rest. Please let us know how things progress for you; I wish you the best!
Ya, been there. Mono *****..But your doctor is doing right by continuing his investigation. Only because it's a little more rare for somebody to get this at your age, and there could be something in the background the reactivated the EBV..Don't get me wrong though, I'm never surprised when it comes to Mono, it can be really severe for some people, others it barely has any effect. Good luck to you.
I forgot to mention that I had had Mono when I was 18, so I really remember how that felt and was sure of myself all along that that was what i was feeling in the background of everything else.