One indication of overtraining is your resting pulse. If your pulse first thing in the morning is 10 or more beats more than normal, you may be suffering from overtraining. Other indications are unusual (for you) fatigue and a lack of enthusiasm for your workouts. Try cutting back for a week and see if you feel better. Cutting back for a week will not only let your body rest, but your muscles will fully recover which may alow you to see more results upon returning.
If you have fever or other such symptoms, see your doctor.