Elation and pain

Two weeks ago I was bouncing around with joy - I had finished Part Three, the "big reveal" in my novel.  After grinding to a halt, I went back and rewrote and rethought and rewrote more until finally it was chugging along nicely and then - at last - it was done.  It's not perfect but that doesn't matter - it's much easier to fix up something bad than write from scratch.  After a few days off, in which I painted my bedroom ceiling (which had gone grey from the mould I'd tried to wash off with bleach)(yes, isn't the life of a writer a thrilling thing), I finally got back to putting words on a page.  I only have two chapters to write, which will be quite short as they barely comprise a scene each, and then there's the epilogue, which is half-written anyway.  My elation at this point had long since waned.  While it would be a great relief to finish this novel, it would also be really sad.  Where will I escape to then?!  As usual, the first attempt at the 2nd last chapter is not going well.  How can I get to the end of the novel and still not know how my characters should act?  I wish I could get some distance from them, stand back and look at them, rather than only being able to see out their eyes from inside their heads.
On top of this dilemma, along with other real-world problems and stresses and strains, I've also hurt my back.  I felt something "ping" this morning while innocuously making my bed and I just wanted to sob with frustration.  I was just thinking yesterday how much better I've been feeling - my foot no longer hurts so much and when I walk, you can barely tell that I limp.  Now I can hardly walk at all.  I'm trying not to wallow in self-pity:  other people, after all, have far worse things wrong with them than a sore back.  Mine will get better.  Until then, I'm chained to my desk and have no choice except to tackle that crap 2nd last chapter.