My Holland Lop does the same thing when he is molting! It always passes and he goes back to his "adult" coloring. He changed a bit from a baby to an adult. As for food just stick with good high quality pellets, and a nice diverse amount of greens!
Good advice. Shaded color rabbits are notorious for going into moults and staying in them. People like to add black oil sunflower seeds to help the coat.