Wow kyparamedic, what a scary event!!
I hope your Grey is still doing well and back to normal. Have you ever used a bird shampoo on her before? It does almost sound like hyperventilation, but could also have been a reaction of some type to the chemicals in the shampoo.
Stress can certainly cause severe symptoms in and of itself even resulting in death, if it becomes severe enough, raises blood pressure, heart rate etc.
I hope all is still well. :-)