To be honest, writer's block is more like writer's jamming signal. Believe it or not, it's not so much a matter of we can't write, it's that we have too much else kicking around that needs to be addressed.
For example, I have a sequel to A Pius Man. I have two, actually; it's a nice, solid trilogy. I haven't touched the lousy thing in months.
Now this is, in part, because I've had to rewrite several bits of the trilogy multiple times. I'm not entirely certain of who or what will survive, and should I be bothered to continue writing if I don't know what changes a future editor is going to make?
Not to mention that I have another book series I'm working on, called Honor At Stake .... at least, that's what book one is called. It's my little revenge on the entire vampire genre, plus a fairly good story, if I do say so myself.
Haven't written one word of that in a few months either. Why? Because it's actually one long rewrite. I wrote a 440-page vampire novel once, where a government agent found himself in the middle of an anti-vampire army in the middle of Brooklyn. Then, I decided to backtrack a little, and made a novel to show the start of that said army; how the relationships developed, how the disparate elements came together....
So, book one is finished, book two is half finished. And I haven't touched that in months either.
Why? Because I keep thinking of books I want to write. And the problem becomes that they're all books in the same universe. All of these characters have back stories in novels I don't know if they're going to get published. In fact, there's too much to be done.
Writer's block isn't a matter of having nothing to write. It's a matter of having too much, not knowing where to start, and knowing that, really, you should be trying a bunch of "books one"s, instead of writing the massive universe you want to.
In short, writer's block is a lot like a jamming signal. There's just too much interference.
In my case, not only do I have the issue of multiple novels, I also have the additional problem of working on a job that requires me to be social. This is a problem in and of itself.
In short, life is getting interesting.