Hi There, I Have To Complete Random Drug Urinalysis For

Hi there,
I have to complete random drug urinalysis for family court reasons here in Australia. My new partner is currently taking medication for a bad back that may contain interaction with methamphetamines.. i have completed a urinalysis test just recently and after always reading negative as i am not a drug user, this time it has come back positive and i am extremely concerned. Is this possible that i have read positive because i have been sexually active with my partner who is taking medication? Could this be transfered to me by his semen?