We all have these days - what makes it YOUR day is what you do with it. Make yourself a deal - try starting the workout for 10 minutes. Then see how you feel. If you honestly do not feel good or want to keep going, then stop. But I'll bet you might feel better, and want to keep going.
And if you are grouchy, nothing helps as much as kicking something. Try one of Sparks Kickboxing videos, or for a jog, or something that requires energy to be used - that always helps me! Good luck, and I hope you feel better soon.