I Use Kadion And Gabapentin,sertraline, Zolpidem,along With Nite Time Cold

I use kadion and gabapentin,sertraline, zolpidem,along with nite time cold meds over the last 6months and have ben to many drug tests in the past with no problems always complyant. went in foe a hair test andnow there saying that I have hydrocodone in my sample. I honestly have not taken any in over a year !!!! what the hell went wrong? thanks Luke