Sickness out of nowhere!

If there is one thing I hate its getting sick all of a sudden for no reason at all. That has happened to me once again this weekend. Saturday I biked home feeling extremely exhausted and tired. The next thing I knew I was in bed at 7pm! I ended up waking up at 1am and couldn't sleep as I started to feel sick. At the weekend has gone on, I have gotten worse and worse. Now its Monday afternoon and I feel so bad I am surprised I am able to get out of bed. And worst still, the weekend is almost up, and this week will be a busy week of early schedules at work, to get ready for the new year beginning next week. I wonder why I'm not feeling well. Perhaps I caught a cold from a student, or the weather changes has effected my body. Whatever it is, I know I'll feel miserable for the next few days.