So i have a question about my rose ringed parakeet ?

I had one of these parrots for about a year (bought him when he was 2 months old) so he is still a baby now.Recently i heated some milk in the microwave and the bird since it was out at the time went right after the milk.It was very hot but he still drank it.He dipped his head into the milk and i didn't notice it fast enough as i went to the toilet in the meantime.The next day his feathers were raised slightly on his head and the day after that (in the morning when i woke up) I found that he was scratching his head the entire night.All of the feathers on the top of his head fell out his skin turned black i don't know if he was bleeding or not but he kept scratching his head for the entire day and even though the top of his head looked horrible (it was completely black like it was burnt or as if a wound was healing).He acted normally and didn't seem to be in any pain but his head was horribly wounded and he wouldn't stop.he will probably scratch it while i sleep again tonight.I apologize for my horrible english but its not my native language and any advice you could give would be much appreciated