It turns out that there have been triggers, and very specific ones. As a person who struggles with body image, I was very distressed by photos taken of me at a party in December. I don't feel as large as I look in the pictures, and seeing them and realizing that's how others see me was gut-wrenching.
Let me explain visually, because I find this fun and I don't have to type as much:

and a sort of cute nerdy librarian type like this:

Okay, now you can understand why my self-esteem plummeted, right? Yeah, I felt really crappy, really unattractive, zero sex appeal.Really unfun.
Of course, there are people on the interwebs whose job it is to make me happy with my body right this moment. I pulled the photo of the punk rock chick above from one of them (thethickness.tumblr.com, but DO NOT go there if you're offended by nudity or provocative images, because many of them are NSFW (Not Safe For Work, i.e. sexually explicit]), and the illustration is from JenOaks.etsy.com, who's made an incredibly gorgeous calendar of pin-up art which IMHO is even cuter than the Elvgren or Vargas originals because the girls are curvier.
And lastly, something that appeals to the confrontational punk rocker in me: