I've been prescribed oxycodone 10 mg for months. While I was taking it, I realized I was going to run out before I could get to the doctor for a refill and a drug test. So, I urinated in a clean container, put it in the fridge for around 2 weeks. On the day of the drug test, I took it out of the fridge for a few hours and then I heated it up to correct temp and away I went to take a urine test. The doctor comes in and said I didn't show any oxycodone in my urine but I did test positive for tramadol!??? Why?? Help!!