Have you been to the dentist?
I was tired and run down for a while. At the time I was driving an hour each way to work, so I figured I wasn't sleeping enough. But when I changed jobs and was only driving 5 minutes, I was still tired. The new job had good dental, not having been to a dentist in a long time I went in. Being a new patient he took x-rays and found an impacted molar, the roots were all rotted. After he yanked it I felt great.
Just my .02