Hi, it sounds like you're having a re-activation of EBV. This is more common than most people think, especially if you've been under a lot of stress or have been otherwise ill/unhealthy. Or, as sporque said, if this was an initial bout of mono, it could still be some lingering symptoms from that. It's unfortunate, but EBV can be a VERY stubborn virus; some people can take years to fight it into dormancy. Add to that the fact that, once you're feeling better, you're now out of shape because you weren't couldn't do anything for a long time!! So it may feel like this is your new lot in life, but it's really not! The key is to make your recovery as gradual as possible. Easy to say, not so easy to do! If you can keep track of the overall progress you're making though, that can be a big help in your day-to-day dealing with EBV. Hope you start recovering soon!
EBV really isn't a diagnosis. If it was, over 90% of the population would be diagnosed with it. It's a latent herpes virus that eventually most people come into contact with. Some unfortunate people have a bad reaction with the virus and come down with Mononucleosis, which is what I'm assuming your diagnosis actually was. I just wanted to clear that up so you didn't confused your readers.
But to answer your question, Mononucleosis can take a little why to clear up completely, in older people especially recovery can include "ups and downs". These are fairly normal and month by month will get weaker and weaker until you are back to your old self. So NO, this is NOT your lot in life now..Mono is a temporary self limiting illness.
Source:
-Mayo Clinic Desk reference guide
-My Doctor.