This could be multiple things, it just depends how acute it is. I’d always start with not touching any parts poking out, and icing in intervals of five minutes, then go to the ER or A&E, because it would be anywhere ranging from a sprain, to a severe fracture, maybe even a low level break.
There’s not much you can do but call the cops on him or try bringing a guy bigger than him to her house when she’s getting abused by him or get her a tazor or pepper spray
