Suddenly strange sounding crow - why?

[MIChickandGuinea]

One of our roosters suddenly sounds bizarre, like he has a sore throat. His crow has gone from the , piercing, strident sound you’d expect from a rooster, to a strange croaky sound. He’s still tootling around, eating, sparring with the other roosters (gently), and all. But as the day has passed, his crow has gotten quieter and lower and stranger. It actually sounds the way one of our roosters did when he was just learning to crow. But this guy is a year and a half old. He is a bantam - silver sebright. Any experience with this?

 

[Wyorp Rock]

Can you post a video? upload to youtube and provide a link.

Look inside his beak to see if there are any lesions, plaques or canker. Check his crop to make sure it's emptying overnight.