Amitriptyline (Elavil) is an anti-depressant, I haven't heard of it used for fatigue and sleep issues. I took it in the early 80's but was allergic too it - but that was long before my Lupus!
Mostly I think polyarthralgia is just the fancy medical term for stiff/sore joints -- a symptom that is very often found with Lupus and various other auto-immune diseases -- not a diagnosis or disease.
Here is a good discussion about
Most rheumies do a sleep study to be sure of what is going on - then sometimes try a sleep aid of some sort to make sure you are getting deep restorative sleep. Plus prednisone to help with the inflammation because that is probably what is causing the fatigue.
Is your rheumy well-versed in Lupus? I ask because he seems to be treating you in a somewhat unusual fashion.
Hope you feel better soon.
Lynnwood, Lupus & Sjogren's Moderator, Dx: 2002DIAGNOSING LUPUS & HW's LUPUS 101
"Life is far too important to be taken seriously." - Oscar Wilde