Is there help for the obsessed?

Well, dear nonexistent fans, you will be delighted to hear that I am about three quarters of the way through the next book in the 'Chronicles of the Brethren' series.  Every spare moment of late has been consumed by this task, I never get to choose when and what I write, rather it seems an idea suddenly comes, and like an addict, I can't help but write; sometimes it is rather inconvenient!  When I actually have time and interest, I have nothing to write about but when I have something I really want to write, the time is not there.  I wonder if there is some sort of psychological disorder specific to writers?  And if so, is there help?