ok, but here's the question: WHAT is the reason? Is it something reasonable, organic, plausible? I think so. Does one event set a chain in motion? This is what I started with, a traumatic event and what would happen after. Or is the reason things happen merely to give you another thirty pages of problems for the character? I have one scene that could come under that heading and I am working on either weaving in a good subplot to support it beforehand or cut it out entirely. Either one is a reason, but the latter is generally a bad reason; things should remain within the realm of plausibility. You have some leeway of course, you're writing fiction, but you just used the "piano on head" example yourself, so you know there's a line....
where the line is is hard to answer in concrete terms, but if you go "really? wtf!" while YOU'RE writing it, you probably know you're in trouble. Nothing has reached WTF levels, yet. LOL. On the other hand, I try to remind this is fiction and it's okay to take some liberties, but to only get my characters in trouble, not out of it (to quote that famous author I can't remember.)