Answer:
Fashions change, but what can a person wear that is never out of style?
An action done on mosquito bites
I am black when you buy me, red when you use me. When I turn white, you know it's time to throw me away. What am I?
I have a brother. However much we run we do not reach each other.
Whoever made me doesn't want me. Whoever bought me doesn't need me. Whoever uses me doesn't know me. What am I?
Give it food and it will live, give it water and it will die.