We are in a relationship but in a fight right now…should I call him?

Of course you should. If you are in a relationship with this person then you obviously share a common interest in each other. Fights always happen when two people try to form a union. There will always be moments of compromise either by you or your significant other. If you want to continue in a relationship with this person you should call him. No fight should ever be so fatal as to sever the lines of communication between you.