Hi i am an English guy with a Polish girlfriend.
I recently got beaten up whilst i was with her, in England by 3 Polish guys,
If it makes you feel better...some polish guys can beat up people despite their nationality. Even if you were polish , they might've done the same.
I think that there might have been an unclear situation between them, i mean your girlfriend and those guys. Maybe she doesn't tell you as much as she should...? Better ask her.
Oh, and hope you get better soon.