Vaccinia virus is the virus that is used in the small pox innoculation. its possible the virus has taken up residence in your body and is now attacking you.
please not that i am not saying this is the case, i am just putting this out there as a possibility, something for you to consider.
my advice to you is to get tougher with your doctor. dont take no for an answer when it comes to an MRI. SOMETHING is wrong with you! dont let them poo poo you and ignore you. demand an MRI and dont take no for an answer. dont let them tell you its too expensive or whatever. its YOUR LIFE! dont let the buerocracy kill you. the squeaky wheel gets the grease, or in this case the demanding patient gets the MRI.
also you might want to get on a full program like Dr. Schulze 's incurables or Dr. Sutter's basics program.