I'd get a portable nebulizer and some 3% hydrogen peroxide. The mini nebulizers are inexpensive, you can get one on ebay for 25 bucks or so. Make up some saline, add some food grade H2O2 ( 3ml to 225ml saline ) and do a few 10 minute sessions before taking the test. Or a cruder way would be to get a little spray bottle and fill with the same formula as above and breath in the aerosol.At six weeks I'd say detecting viral particles is unlikely. If it were me, I would not take ivermectin, or I would just take 12mg one time (half life is long). I would take a cotton swab before your PCR test, put it in peroxide, and try to clean out the nostril.