Can you fail a drug test by people smoking around you?

I have been quit from smoking weed for nearly three months. However, people have been continuing to smoke (in a large, open room) around me. I was wondering if this could cause any or enough thc to be in my system to fail a urine test. Also, could anything else cause a false positive result? I have taken Benadryl sinus, Nyquil, Ibubrofen, and otc Heartburn pills. Will they be able to tell if these drugs caused a false positive?