Kelly: For what it's worth, I agree with Jack and JoAnn. Put away the running shoes, forget the weekly 5K races and go do something else for a few weeks. You're getting to the compulsive stage and that spells trouble. This is temporary unless you allow it to become permanent. You're running now because you think you have to, but you started because it was something fun that you wanted to do. Do cross-training (rowing, elliptical, weights, bike, swim), go for walks, anything but running.
You also said "I have to start HM training soon". No, you don't have to start HM training. Maybe it's time not to do HMs, especially since it appears that you don't want to at this point. I don't know where you live except that it's obviously a cold-weather climate, but there are probably lots of HMs through the spring, summer and fall months. Give yourself a vacation from running and, as long as you're staying active, you won't lose fitness. You may actually be strengthening muscles that will help you run stronger.
--Steve
Completed in 2012:
The Qualifier HM, Midland MI, May 2012, 2:58, 80+ degrees
Dam to Dam 20K, Des Moines, IA, June 2012, 2:17, PR for this race
Garry Bjorklund HM, Duluth, MN, June 2012, 2:20
Fox Valley HM, St. Charles, IL, 9/16/12, 2:23
Des Moines HM, 10/21/12, 2:19
Tentative plans for 2013:
Wisconsin (Half) Marathon, Kenosha, WI 5/4/2013 (registered)
Dam To Dam 20K, Des Moines, 6/2/2013 (registration opens March 20th)
Grandma's (Half) Marathon, Duluth, MN, 6/22/2013 (if I get picked again in the lottery)
Des Moines HM, 10/20/2013 (registered)