I'm sorry you are sick - hope the situation resolves quickly. I really don't think you owe this building manager any loyalty what so ever. Call the police now. you are not obligated to do what this bldg mgr requests.. you have already informed him of the situation, what exactly does this person intend to do with another report of new smells coming out of the apartment in question ?? If he isn't in with them, he is afraid of them. Either way - not good for you and your health at all.

This is not a promise to keep - this person doesn't have your best interest in mind. Call the police and let them investigate.

Good luck