Will over-the-counter medicine for tooth ache that has benzyl alcohol in it cause false positive on 80 hr test I take?

Toothache. OTC remedies will not cure infected tooth, only mask the symptoms as the infection worsens, spreads, and can farm other tissues. You have a more serious problem than alcohol residue in a blood test. Seek professional care now.
Get to source. Need to get to the source of the toothaches, and not treat the symptoms. Try and get a dental appointment asap.
Definitely, no. While some OTC meds does contain some benzyl alcohol, it seems highly unlikely that it would show up on a urine drug test. The modern drug testing is done by the mass spectrometry. It can differentiate between benzyl alcohol and ethyl alcohol and would not cause false positive drug screen.