It was tinea versicolor, but it is dead. No worries, you don't have sun damage. Tinea versicolor is a skin fungus that some people get in the spring time. And it dies after summer. While it is alive it is not really noticeable. Maybe a little red, slight itchy, and you could slightly feel it from the touch IF you were looking for it. The reason why you have the white spots now is, you got some sun while the fungus was alive, and it does not allow the skin to take on pigmentation. Then later on it died and you are left with the white spots. You could just go get a tan and they would be gone after 4 or 5 sessions. Just keep in mind that Tinea versicolor season is coming around again, And you can get the fungus from an unclean tanning bed. Like someone else said the treatment is Sulfur. Which is the active ingredient in Selsun blue, but only 1%. With a prescription you can get a Selsun blue at 2 %.