Hi Alex,
It definitely sounds like he suffered some type of injury. I would take him to an avian vet to be checked out. It’s great to let a pet bird fly, if they can do it safely. But with any pet bird, he should always e in his cage when you aren’t home or when you can’t supervise him. Leaving a pet bird unattended is much like leaving a toddler unattended. Parrots are just smart enough to get into trouble. And when the owner is away, they are much more likely to get into something that they would not try if they know you are home. I hope everything checks out and this is something he can eventually recover from.
Take care,
Brenda