I ran into a problem in a game today when it came to Protection from (Energy). There was a character who had a bomb inside of them and the party though it would work if they cast Protection from (Fire) on them to absorb the blast damage. I ruled no, saying that Protection from (Energy) only works for external damage.
However our sorcerer has a spell called Burning Blood that deals internal fire/acid damage. If Protection from (Energy) spells only protect from external sources then Burning Blood would be immune.
I know it's splitting hairs, but unfortunately it's come to a point in the campaign where something as technical as this must be asked. Do Protection from (Energy) spells protect against internal or external sources?