Hello Lynn

This is definitely a question for your doctor to answer. Only he knows why he is choosing this treatment for you.

In the meantime I am going to give you the link to our Chronic Pain site.  The community leader there, Karen Richards, knows a ton about fibromyalgia and may be more familiar with the various treatments.

In researching your question it seems that doctors do prescribe antidepressants such as nortripyline for fibromyalgia.  These medicines can treat pain and improve sleep and mood disturbances seen in fibromyalgia. 

Here is an article from our chronic pain site about the use of antidepressants to treat chronic pain related disorders.

I have taken this drug years ago but not for fibromyalgia but for major depression.  It worked fairly well for me for the short duration I was on it.

Let us know if you need any more assistance.  Thank you for your question.