Seeking writing advice: how to keep writing

I've been having some shoulder pain for the past couple of weeks, which I've seen a doctor for. I've also noticed that I haven't actually written anything new for my novel, "S.I.", for almost that long, and have just been posting chapters from my buffer to the forum I post them in.

Given my previous attempt at writing long fiction ("Myou've Gotta Be Kidding Me"), I anticipate two likely courses. One, pain sucks, and when it goes away, my writing motivation will return, and I'll get back into the swing of things. Or two, my writing engine has run out of motivation-fuel for this story generally. In the latter case, I think I can avoid leaving the story entirely unfinished, though there would still be all sorts of dangling plot threads and unsolved mysteries; I should be able to muster up enough typing to have my protagonist finally feel overwhelmed by everything she's facing, retreat to Elliot Lake, and jump to my intended finale. It's far from a perfect solution, but seems better than putting the story on permanent hiatus (or more formally cancelling it) without any finish at all, as I ended up doing with "Myou've".

I'm hoping it's the first course. What I don't know... is if there's any way I can tweak the odds to /favour/ the first course.

Any ideas?