That looks like crossbeak. It can seem to appear in a very short period of time, but is a malformation of the skull and jaw which when left to grow will get worse over time. I have a crossbeak bird that I have not culled and she gets along fine as long as she has a deep feeder. It can be genetic, so I would be not breed a crossbeak bird. It may be an injury as you suspect. If it is I am not sure how the bird would be able to eat if it can't use its jaw.