Help with a chronically ill rooster

[MaeM]

Guys, I was giving him antibiotics with a syringe directly on his beak and I saw white plaques on his throat. I can't take pictures because he moves a lot. But what could this mean?

Also, can you confirm that I'm giving him the doxycycline correctly? The vet told me 10mg/kg and the rooster weighs 3 kg, so 30 mg = 0.03 ml (the syringe is in ML).

 

[MaeM]

UPDATE: I found a vet. Turns out the rooster had wet pox.

A few hours ago, he started making gurgling noises, he had something that looked like a seizure, and finally died in my arms.

What the f*** was that?