so close to quitting

I have never been this close to quitting my PhD. The speed at which I have been able to clearly see the alternative, non-academic path is really alarming: about 36 hours from irrational panic to unnerving calm.
(The surface of the sea, seen from my window, has also been flat and opaque, shimmering and restless: the weather dark and light, yes and no.)
This morning I went into Kemptown to do some chores. I was unable to meet the eyes of anyone in the post office, the grocer - an old woman was talking to herself, I felt sick. I walked back up to the flat and felt certain I was on the edge of a nervous breakdown and should be signed off work.
(Except when I imagined what I might say to the doctor, the unfolding internal scene felt like a silent film mime of mental illness.)
Then a chain of internet searches, like the snapping of synapses, led me to the search-term (thought): should I quit my phd?
There were people commenting on the post who were just like me, stopped short by horrible crippling doubt. Will I get a job? Will I go insane? Am I an academic? Is it worth it?
Now I can't do any work: I love the work, but I can't bend my words into a useful shape. I can't write about this stuff and also engage with the academy.
Have I simply switched the tracks from quitting a job, to quitting the PhD? Am I on the wrong or right track now?
My job though, as a research officer, highlights the very worst of the academy: getting funding, being in the right 'sandpit', being the one they suggest to help out, being alone and churning out page after page of fundable, safe 'outputs' with massive socioeconomic impact. I WRITE ABOUT NOSTALGIA.
I don't think I have the ego, I am not a cat (see http://www.triarchypress.com/pages/Herding_Cats.htm ) I don't want to be working in Marx's sausage factory churning out new ways of saying old truths, churning out people who can pass exams.
If I don't do the PhD, I am back at square one. No right to write.
Still - the PhD is just not creative any more.