mitochondrial neyropathy

i'm a 68 year old man diagnosed by your dr levin in 1997 (my records should be available there) with probably myasthenia gravis. it was later confirmed by the dent clinic in buffalo and my current neurologist. i have been treated with IVIG for several years. recently, a physical therapist who is a last year OD student suggested that i should investigate mitochondrial neuropathy. in recent months my strength and energy level has declined dramatically and all my major muscles are so extremely painful that i must use fentanyl patches (75mcg). i am able to be out of bed for only an hour or two and am unable to walk more than a few feet. i am overwhelmed with exhaustion - huge yawns, burning eyes, loss of voice, send me to bed. i have been having cognitive problems "losing words", forgetting, etc. i had cataract surgery and was seeing well, but i can no longer read well and have lots of "floaters". is this worth investigating? should i consider another trip to the cleveland clinic?. is there testing that could be done locally? i am very concerned that my activity level will continue to decline and i'm pretty close to bedridden now. i really need help.