How can i treat white spots in my face?

Ok so this is not the first time this has happend to me. Ok I noiced last year that after summer started and I went swimming a lot I got burnt in my face then after it went away there would b a white spot left were th burnt was! This also happend on sevral spots in my face! But then I noticed that during winter time they whent away! So this summer I'm just noticed there coming back! I have like 2 spots! How can I treat them to go to my normal skin color??