Drugs? Or....

Kt

So I live in not so great community and in parking lot I seen people sell and buy drugs. And I smell weed alll the time on the way to my door. I’m 100% sure people above me smokes. But anyways Ive been smelling this weird smell at different times and I’m wondering it can be some strong drugs? Like burning or smoking something. I only know what weed smells like nothing else. It’s coming from my kitchen/ dinning room vent. I smell it with or without AC on. Maybe stronger when AC is on but doesn’t smell in any other rooms. It only lasts for about 15-30 min at max. I have a son and I’m pregnant I really wanna know if this is something. I have smoke and every detectors I know in this unit. To explain what it smells like the best I can is first I smelled it I thought my sons plastic ball was “burning “ near the oven even tho it was off and no balls found. Or describe it as ziplock bag melting near the gas grill. It’s very strong I stood under the vent kept smelling to see if I can think of anything after few sniff my nose hurt really bad. I don’t even know where to post this but giving it a try here. What can it be ?