got a false positive drug test and my dr. cut me off

i have seen the same dr. for five years now. i always have used the same pharmacy. i do everything by the book. i never abbuse my medication. infact it usually last me several days longer. recently i took my kids to disney land in florida. i was really sick with a bad sinus and upper respiratory thing. i normally never take anything took strong over the counter since i have a valve in my heart that doesnt function properly that i have to take calan(verapamil)for. but we where gone for 12 days. so i had to do whatever to muddle through. i tried alot of over the counter meds during about two weeks. when i returned home i had an appt. with my dr. i always do blood work and a urine drug screen. i was notified that i had failed my drug screen for methamphetimine. i think i spelled it right. i made another appt. w my dr. to discuss that it was not possible. for me it would be like playing russian roullette. knowing me for all this time he said he honestly believed me, but unfortunetly he couldnt write my pain meds or xanax anymore. i have know idea what im gonna do. the next dr. wont know me and will probably think im a addict trying to get high when he sees this in my record. i really need my meds as i have two crushed discs in my neck, two bulging discs between my shoulders, a degenerative disease in my spine is also pinching nerves in my lower back. i also suffer from post tramatic stress w severe anxiety and muscle spasms. i have fibromyalgia to top it off. has anyone been in a similar situation? i am so torn up and my anxiety is so bad over all this i am beside myself. not to mention totally embarrassed. do i have a chance? what do i do? anyone please give me some uplifting words and good strong advice.