Is there a connection: Myoclonus, Erythema Multiforme, and Herpes Zoster?

My Father in law is suffering with a terribly painful and debilitating disease.  He has received many different diagnoses, and some of them we are sure are accurate, but some of them seem to be just assigned to cover symptoms. He is heavily medicated, considered disabled and is no longer able to work.  We are concerned that with so many different symptoms, diagnoses, and doctors, what he actually has might be treatable, but never diagnosed because it has been lost in the shuffle.

He has chronic Herpes Zoster.  The shingles have come back 7 times in the past 17 months and he now has continuous Postherpetic Neuralgia.  In addition to the Herpes Zoster, he is also a carrier of Erythema Multiforme, which he has been hospitalized for in the past.  He also has symptoms of neurological damage or a serious neurological disorder.  He is also suffering from sever and acute Myoclonus.  His other symptoms include severe and acute back and joint pain, swelling of his hands, extreme exhaustion and debilitating fatigue, an unelaborated upon thyroid condition, and several other symptoms.  Now, doctors are concerned that he also has some undefined autoimmune disorder.

In 1993, he was hospitalized with Erythema Multiforme, which formed on his lung tissue.  The exact cause and form of the disease were unknown. He was living on a US Military base in the Azores at the time.

This sever situation all started about 17 months ago.  He was a very active and healthy 50-year-old.  He was a scout master, devoted husband and family man raising 3 teenage boys, and working full time as a church minister.  He contracted a "classic" case of shingles.  The first case of shingles went untreated for more than two weeks because he thought is was simply a back problem.  They went from his hip, down the back of his leg to his foot.  From there, the shingles wrapped around to the top of his foot and his doctors noted that this development was "a bit unusual."  Approximately 6 weeks later, his hands started shaking.  Soon after he began experiencing numbness in his hip (the same side that had shingles) but sometime later, the numbness spread to his whole hip and down both legs. This numbness and strange feeling has now also spread to other areas.  It is acute numbness and is continuous.  He has also mentioned that parts of his face feel strange and unusual.  Not much later he began experiencing Myoclonus.  These Myoclonus attacks have grown progressively worse.  They are extremely painful, usually beginning in his stomach and moving downward toward his feet.  These attacks are also lasting for 4+ hours per day now.  

They have speculated that he may have a very rare form of Parkinson's, but the tests for that were inconclusive and doctors were vague about the results.  We feel like the doctors are giving up and just giving him medication to mask the symptoms, instead of looking for the source of the problem.

(We have recently found out through some channels that during his time in the Azores, everyone at the military instillation there was given beef from Great Britain that was later found to be contaminated with prions disease.  Because of the limited research and knowledge about prions, we are unsure if any of his current symptoms could be related.)

Is there a connection?  Can anyone help? Is there hope of treatment/recovery?

If you have any answers for us, we are desperately searching.  We are running out of doctors to see and options for controlling whatever is destroying his body so quickly. Please let me know as soon as possible if you have any advise or help to offer. Thank you for your time.