Um, just why is he reacting to ONE complaint from a new tennant, but not doing anything about the pig who tried to burn down the bulding? He really can't do anything about your cats if he's not doing anything about the bum downstairs.. that would seem to me to be legally wrong. You could say that he's allowing the man downstairs continue because he's a man, but is making you do something because you are a female.

Also, is it possible that the other tenent is using the odor as an excuse to leave? Maybe he realized the bum living downstairs isn't going to get better, and since he knows he can't get out of a lease based upon disliking the guy, he tried to get out based upon an animal smell.

Good luck! the other suggestions were great!