I have a study done by the VA in my journal which found that a whopping 44% of patients taking opiates were found to have tested negative. this study was done a few years ago so the results now would most likely be shocking.
I hope your doctor has not dismissed you. it can be difficult to find a doctor that will treat you after this happens.
You can have a hair follicle test done. The results will show the past 60-90 days what you have taken.
You can order a test offline and have the results sent to your Doctor or have it done in your town.
I hope it works out well for you:)
Here is where you can find the study I was referring to.
http://www.medhelp.org/user_journals/show/97621/False-negative-urine-test?personal_page_id=863283