Check the poop of your teenagers. Are they sitting around fluffed up, not terribly active?
I'm wondering if you don't have some coccidiosis going on.
If there's any sign of blood in the poo, or if they are fluffy and inactive, get some Corid or Amprol, STAT.
You need to get them on powdered milk in their feed if it will take you a few days to get the Corid.
If they are still active and not fluffy, is there an older population of birds out there, too? If it's just them, it could simply be a comfort thing, but I'd guess they'd be wanting the sunshine.
Go, peeps, go!!!