What type of virus reappears when I'm tired and stressed?

For some years I've had what I guess is a virus that makes me exhausted, headachey, with swollen glands and takes a couple of weeks to go away. It arrives after I've been low for some reason - sleepless nights, stress, too much work etc - and then I feel like a zombie and can hardly function until it goes again. My tongue is yellowish and the back of my throat is reddish BUT that's not unusual for me either. My tongue is always furry anyway. My doctor said she didn't know what this is or how to help me, she said "get enough rest" and that's it. She thought it might be recurrent glandular fever, but I don't know. Isn't that a childhood disease, and this only began about 10 years ago for me. Can anyone suggest anything?