Mark may be on track. I don't believe there's anything in the Resolve work flow that would cause what you're seeing. It's more likely this was caused by something outside of Resolve.
My Biases:
You NEED training. You NEED a desktop. You NEED a calibrated (non-computer) display.
It is a mystery as to what caused the change- but I was able to locate the original files on an old backup field drive. So all is good. Thx for the input