Pot smell coming into apartment from ... Somewhere

Hey,

My wife and I live in an apartment, in MN, it's mostly great except, a couple times a week our second bathroom starts reeking of weed. It affects my wife's asthma, and it's just kinda annoying (we are cool with weed but on a "don't be a dick about how you use it way", and neither of us use because I shoot firearms competitively, which itself is a reason I hate having my apartment smell like weed). I've multiple times to the office, but without knowing where it's coming from (can't seem to smell it in the hallway from any unit) they say they cannot do much...

Is there a way to make them do something... Like filters in the bathroom fan or something? Technically smoking (of any kind) is allowed in units, but it shouldn't affect other tenants from what management has said.