This Is my 3yr old cockatiel, Ollie. He has been fine all day and I just got home and there was matted feathers and somthing that looked sticky? All over his face. I looked at what he could have gotten into but I left nothing open. I'm afraid he threw up or somthing. Please help, it's night here...

So for the past 5 months my cockatiel has been scratching around his head and sneezing uncontrollably...I’ve taken him to the vet 3 times which has been very expensive. currently he’s on medication but it doesn’t seem to work. does anyone know what I can do