Hi Brian,
One of my boys (also 2years) has white spots liek you cat below his ears where the fur thins. It sounds like what you described and he has not always had it. I tried to take photos so you can see if it is the same thing, however Ossie wouldn't keep still. Two photos are below but are blurry due to his figgiting.
I took him to the vet yesterday and she thought it was just natural pigmentation that is noticable only because the fur is thinner there and it is nothing to worry about.
When the results of the culture come back could you let me know the results as if there is a fungal cause in your cat and you think it sounds similar I'll take Ossie back to the vet.
Hopefully we both have nothing to worry about
Best wishes,
Emma