I Just Came From My Pain Dr And Could Not

I just came from my pain dr and could not get my oxycodone 15mg because my drug test came back and said it shows methadone i have never had methadone in my life I am on sertraline 100 mgs inhaler Ventolin hfa 90mcg clonidine .2mgs lisinopril 20 mgs sometimes melatonin 5mg please help me to understand this I am so upset about this can u tell me how this can be thanks doris