I’ve been thinking about it for a while, so, uh, I don’t know if anyone have told about it before and I haven’t seen it so…
Corsets.
There’s various options of using it on whumpee. Maybe previously Whumpee’s ribs were broken so now they’re wearing a medical one, given by whumper whom didn’t wanted to lose their whumpee soon and lowkey tries to heal them, but every time whumpee does something wrong whumper casually ties their corset tighter, making their ribs hurt even more, knitting bones fragmenting and causing pain worse, letting them to do shallow breaths only.
Maybe whumpee is wearing a corset as a punishment. An extremely tight one, squeezing their waist and making every breath they try to do painful, oxygen shortage makes whumpee very weak and vulnerable and even force them to faint. Ribs breaking. Organs displacement. Yeah, it hurts, a lot.
Or maybe whumper wants their whumpee to be pretty, but whumpee isn’t really slim as whumper wants so they force them to wear a corset to make their waist as slim as they want?
There’s a lot of options to play with, really a lot. So feel free to add more!