My Wife Is Awfully Tired All The Time And Always

My wife is awfully tired all the time and always exhausted. Much of that from chronic pain: lumbar stenosis, sciatica, diabetic neuropathy, fibromyalgia, loss of thyroid through surgery when thyroid was found to be cancerous, after effects of 34 radiations to neck area as post thyroid cancer treatment. What type of doctor should she be seeing to address the above, especially the weakness and sleepiness issues?