I don't know what sort of medical problems you have, but some types of pain that can be helped by amitriptyline can also be helped by Cymbalta. Cymbalta goes fine with mirtazapine.

Another option would be to find another GP (if you're allowed to do that.)

I take Cymbalta 60 mg for fibromyalgia and autoimmune arthritis pain. It works well for me. It's also prescribed for my depression.

Effexor is often prescribed for chronic pain, but when I took it, I had to take a very high dose (375 mg) in order to get the pain-relieving effect.

Some other psych meds that people sometimes take for chronic pain are Pristiq and gabapentin.