Our golden retriever never used to be afraid of thunderstorms, however, now is terrified of them! We can't figure out why or seem to calm him down. Suggestions?

You have likely already asked yourself this, but what happened to him to change his behavior? A loud dump truck gate slamming closed could have hurt his ears or something equally trivial-seeming.

If he likes cuddling, during the next storm let him.

Having his hearing and ears checked is probably a good idea, too.