Doc is telling you true.
The vast majority of "squealing" is vibration enhancement.
Pull the pads out and take a good look at them, the backs, the ends and the sides. Anywhere you can see contact marks, paint scraped off, shiny metal, etc; then you have been getting metal contact.
The pad will set up a vibration on the piston and transmit it to any metal contacting piece which gets amplified by the caliper, etc.
So lightly lube the retaining pins, the edges of the pads where they mount in the caliper, the back of the caliper where it touches the piston. This will take care of the metal squeal.
Now cold brake dust squeal(first brake application in the morning) can be alleviated by a slight bevel cut to the leading(and trailing edge if it happens when backing up) on the pads. If you grind them at the bench, make sure you keep your air intake covered with a paint mask or something.
I have encountered and mostly conquered, as my experience grew, brake squeal on Hondas, Acuras, MB's, Pontiacs, LBC's(Triumph, MG, Rover) Porsche and Mercedes Benz with regularity.
So, please share my experience. It costs you almost nothing, just a little investigative teching.