Medical marijuana permit questions?

My father suffers from chronic back pain and has received a permit to grow and smoke (or ingest) cannabis for relief.

Since I had my son (epidural FAIL) I have suffered chronic back pain as well. My father printed out a form for me, so that I can take it to the doctor and have it signed and thus be legally able to use cannabis therapeutically.

I must admit that I have smoked marijuana for the pain and it has worked significantly.

I inquired on this site before about excessive back pain; this has been going on with me for over a year and a half and I have not yet seen a doctor for it.

I am covered under my stepdad's insurance and I am hesitant to have this form signed, as I would rather keep this situation a private matter.

I also do not know exactly how to go about having a doctor sign this form, and whether I need a record of the history of my condition for the doctor to sign it. (the only record would probably be that the epidural was administered, and the nasty scar on my back from it)

Any advice or personal experiences would be appreciated.