I had it in high school. It was the worst. Terrible, ulcerated, blistered sore throat, so bad I could hardly swallow. Awful fatigue. Fever. Enlarged lymph nodes. And I had an enlarged spleen. It lasted about five weeks and then I got better. It was a drag because I couldn't play any sports while I was sick, and it happened when I was on the girls' basketball team. Like any virus, it just has to run its course. And for the rest of your life, your bloodwork will reflect that you've had exposure to the Epstein-Barr Virus, which is the one that causes mono. Be sure and rest and take it easy like you're supposed to till your symptoms ease. Feel better soon!

Info in case you're interested:
Mononucleosis -- familydoctor.org