my dr put positive cocaine test in his notes, will I lose medicare?

Most likely not, though medicare will recieve all of your doctors notes, and as a doctor myself, we can refuse to treat patients if we wish(I mean in nonemergent situations). I never do clinicals since I am a radiologist, but back when I was a intern/resident, I probably would not have treated you as it goes against my own morals, but I am sure other doctors will be willing.

If the system works right you'll lose it but who knows these days.

Probably not, but you might find a doctor unwilling to treat you if you need medical help. Is that worth it to you?

doesn't ss receive all dr's notes?

If it is medical you shouldn't !!