I Had A Drug Test For A Temp Agency I

i had a drug test for a temp agency i pass got some work. i almost got a job full time but this time i did not pass the drug test. i am not taking drugs. i tested for thc this cant be happening to me. these are the drugs i take back pain gabapentin oxycodone/acetaminophen. lisinopril atorvastain calcium and carvedilol. help me understand why me.