You've described EXACTLY the way I feel. The way I describe it to others is ya know that nervous feeling you get before a big test? I have that ALL the time. Then all that worry drains me mentally so I end up tired all the time.
Besides medication, the only thing that worked for me was to have something to look forward to. Even if it's curling up in bed with my cat at the end of the day, it helps ease the worry.