What Causes Lethargy, Burning Sensation In The Right Leg And Back Pain?

Hi. I have had the following for up to 3 years: Demylination of nerves (confirmed via MRI), general lack of energy, will fall asleep often in early evening or late afternoon despite averaging 7-8 hours sleep a night. I have a significant burning sensation in my right leg that hits sporadically, typically several times a day, sometimes it hurts so bad I am almost in tears. I also have problems with my back locking up, sometimes standing, sitting, or laying down. I have been on lyrica (8 -x100 MG a day) for about 18 months now. Also, my testosterone and thyroid levels were way below normal limits. On Nature-throid for that. I have also been on BiotE for about 2 months, with no improvement noticeable, in fact I ve gained 10 pounds since I started. I was a lifelong athlete, competing until my late 40 s. Two years ago when this started I was not on a single medication, now I take many. I still exercise 3-5 x a week, but the back and burning pain issues often cut that short. I am 63, male, 5-11, 190 pounds, was 175 until last spring. Suggestions?