Why is my betta fish (siamese fighting fish) not eating?

He stopped eating the normal food pellets when I brought him home from college 5 days ago. I have also tried to feed him freeze-dried blood worms which he also eats, yet he refuses to eat them too. I could try feeding him the freeze-dried brine shrimp that I have, but he usually doesn't eat that. Is he not eating because he isn't used to the new setting yet (I know this can happen)? Also, any recommendations on how I can get him to eat?