This sounds like a general diagnosis of depression, or may simply relate to the feelings of depression based on a dozen factors.
You may be responding to mental or physical exhaustion, either from trying too hard compulsively or simply just having a "breakdown," (not in the cases of insanity, but you know what I mean.) These things happen to everyone, and are easy to resolve.
It may simply go away in a matter of time, or you may want to consider occupying yourself with something more positive to help it disappear, your mind may be too reliable on the compulsive negativity you're feeling right now, and doesn't potentially find anything else positive to be fulfilling.
Medicine really isn't the solution to depression, but if it gets to a very concerning state, I'd suggest you see help from a professional. But if you feel as if it's not that much of a deal, then maybe you should be sufficient and wait to see what happens. These things don't last long unless you provoke them to. Which I doubt you want to do.