Take a few days off and see how you feel. If its bad I'd say take a week or two at least & go get a life.
Usually your body will tell you -- I had a point where I experienced severe overtraining for a competition and I hit a point where I was an emotional wreck, gained 30 lb and couldn't make it thru a training session w/o either breakign down & crying or becoming completely exhausted. This is pretty obvious. I was so frustrated I just stopped trying and lived miserably for a while. It took me 6-12 months to get rid of the weight.
When your body is ready to go back is when you don't get exhausted quickly, don't have panicky workouts where you're trying to push harder and getting no where w/ your efforts. Also if you're sleeping well or if you feel perpetually exhausted (physically or emotionally).
Another thing when people worry about taking time off from the gym - which is usually the cause of the overtraining, and then a further concern when they do finally hit that point of shutdown and still can't walk away. When you do take time off, you are never really "losing your gains" - its all a very fluid thing in terms of 'Size' and 'preserving muscle' - you'll no doubt come back stronger after some time off and also hopefully w/ a few things learned about what led you to overtraining, and a new view of the value of recovery, and even better, maybe you went and got a life outside the gym with your time off.
And then come back & read up on Periodization so next time you don't get burnt the fuck out.