Tried posting last night-Marijuana and Opiate Prescriptions/Workman's Comp

I'll try to sum this up quick. Four years ago this month my foot was run over by a 2500 lb pallet jack. Was quickly prescribed vicodin and placed on monthly visits. Well now I am on quarterly visits and taking Norco 10/325s 4x a day. I sought the assistance of a friend in obtaining my medicinal card so I could ease up off the vicodin (not as fun as one may think to be stoned out of your mind all day, everyday for 4 years on opiates).

This past week I had one of my quarterly visits for painkillers with my workman's comp physician. I was told that due to new regulations put in place by the FDA that I would be subject to random drug testing ( and if any ILLICIT drugs were found I could be prosecuted). I mentioned my medical card. Then my doctor told me that that would be a problem and we have to get me switched to a non-opiate based painkiller since there is no scientific research (or confirmed sci. res.) on the interaction between marijuana and opiates and this could potentially damage my workman's comp case. (I'm not seeking major amounts of money by any means, just pain relief and perhaps a cure for the nerve damage I am suffering from so I can go back to be the active, happy person I once was)

Today, I was informed by a highly trusted friend of mine that they cannot tell me I can't take the marijuana prescribed by my other physician because these two prescriptions were obtained, legally through PhD licensed medical doctors. I have my medical card and all legal paperwork.

I quit smoking on Wednesday because they contacted me about having to retake my drug test (with my busy schedule it is impossible to return to the doctors office for the test until early next week.) and even with my painkiller pills that I'm popping every four hours I am in an immense amount of pain.

What are my rights as a card holder?
Is it possible that if marijuana does show up in my drug test next week that my case will be thrown out or will it hinder my case in any way even though I am a legally prescribed patient?
I don't know what to do and am not sure about contacting my attorney until I know I won't be punished for seeking pain relief elsewhere.

I am planning on getting surgery (as I had a new, outside IME doctor reexamine my foot and tell me that a nerve removal/resection from my foot could take away the pain, leaving only numbness.) this summer when my 18 credits of school are over and I am not so busy with work on top of it.

Sorry this ended up being longer but I wanted to try to not leave any questions unanswered for a quicker response.

Thank you in advance for your advice and insight. I am in a terrible amount of pain and maxed out on my painkillers for the day. Please help!