Well good luck getting a doctor to treat you, knowing you are just going to self treat.
The problem isnt that they went and found some medicine their doctor wouldnt give them. The issue is that they didnt let the doctor know.
If rattlesnake juice is going to cure you and the doctor wont prescribe it, check yourself out, take the juice and there is no problem. Either you trust the doctor or you dont. Either you want their help, or dont.
At best you are giving the doctors bad data, oh this treatment finally started working, I will do it for similar patients. At worst you fix your immediate need and get another treatment that reacts with your snake juice, and you have another medical emergency on your hands.