So, I finally found out what the hell's been wrong with my knee. Apparently, when it first stared hurting (at the back of the knee)back in late September, that was because I'd strained my ACL. Then, when the pain shifted after about a week to the top and outside of my knee, it was because the weak ACL combined with the way I was sitting with my knees bent and feet tucked under me at work (because my desk is badly designed and has no space under it for my legs) pushed my kneecap out of alignment.
Apparently it's a common runner's injury and they can fix it with therapy/exercises. Joy. (But I do get bright blue tape around my knee to prove to my employers that I totally had a reason for that doctor's appointment - not that it's stopped anybody from sending me out to run errands/sending me running up and down the stairs at work repeatedly, but the sprained ankle I had a couple years ago didn't either)
Apparently it's a common runner's injury and they can fix it with therapy/exercises. Joy. (But I do get bright blue tape around my knee to prove to my employers that I totally had a reason for that doctor's appointment - not that it's stopped anybody from sending me out to run errands/sending me running up and down the stairs at work repeatedly, but the sprained ankle I had a couple years ago didn't either)