The mods will probably move this to the medical area, so look for it there if you don't see it here later.

I had mono when I was a teenager, and it did take some time to recover from. I never had any repurcussions after that, but it can take a long time for many people to get their energy back. And for some people there's a connection between the mononucleosis virus and the later development of chronic fatigue syndrome.

Do some research on Google and read about mononucleosis aftereffects and related diseases/syndromes. Then if you're still tired, go talk to your doctor again. There's not much they can do about either mono or CFS, but sometimes just having the symptoms confirmed makes you feel better.