Mono is always possible but usually you stay sick for a long time instead of just a few days. I think it would be wise for you to go to the doctor and get checked out. Your fear of it being something serious more likely than not is unfounded. But you don't want something that might be minor right now turning into something more serious. Go to the doctor and get checked out and if nothing else you will at least be able to put your mind at ease.

You might want to seek medical care. The symptoms you described are usual signs of mono. Learn more about mononucleosis symptoms and treatment here
Emedicinehealth.Com/articles/16277-1.Asp

When you have mono the normal symptons include long periods of sickness such as the flu or cold. You have a rough cough and much drowsiness and also your throat does get very soar just like strep. If you go to the doctors and they say that you have strep please go get a blood test too. If you are on pennicilin or you are on amoxicilin while having mono you get hives and rashes all over your body, which can last up to 2-3 weeks!
So watch out for a misdiagnose because I was reccently misdiagnosed about 3 weeks ago with strep and have now been told ive had mono and have been having hives for 2 weeks

I have mono right now and it is really bad! Maybe its just the kind I have but both my sister and I had it and our symtoms were as follows:
sore throat, swollen lymphnodes, sore neck/shoulders, severe headache, sinus infection, achey muscles all over body, extreame fatigue, ear infection.
As you can see we both had it pretty bad. But the fatigue set in so fast it was crazy! I was a little more tired then usual for about 2-3 days, then I had a sore throat (which went away after 3 days) then all of the sudden I was so tired I couldnt do anything! I slept and laid in bed for seriously a whole week. Your symptoms could be a slow build up to mono, sometimes it takes a while (2 weeks-a few months) to actually get it bad. But you should go to the doctor and get a mono spot blood test done. Its really simple and doesnt hurt. If you do have it I recommend you buy
"monobrex" from monobrex.Com. Its a little expensive but some insurance plans will remburse you with your taxes. I hope you dont have it! Get well soon and take care.