Teflon/PTFE hazards — nearly lost my bird

PSA for anyone who doesn't know — nonstick pans can KILL birds. I found out the hard way when I accidentally overheated a pan and my budgie got sick. Thankfully caught it in time. Please, if you have birds, switch to stainless steel or cast iron.

Did this start suddenly or was it gradual? When my Hahn's macaw did this it turned out to be boredom from lack of enrichment and mental stimulation.