Hi, I Had To Tae A Drug Test Today And

Hi, I had to tae a drug test today and everything came back negative but Benzophetamine I may have spelled wrong but came back positive. I was in the hospital recently for maltruition as well as a blocage so they had me on liquids and also medicine that helps with bowels after released they gave me a subscription for lactose which I tae three times a day. Could this possibly have that chemical in it?