What Are The Differences Between Nortriptyline And Oxycontin?

ok ready for this one. i was in a scuba diving accident two years ago and had decompression sickness---was treated for many hour in a deco chamber. I have no spine damage but have tissue and nerve damage as well as spinal stenosis...including neuropathy in both legs and feet. Docs put me on nortriptyline and oxycontin. i did not respond or react well to the nortriptyline...i had difficulty with feelings of aggression and emotional swings. Then they changed to amitriptyline 25mg/2 per night. Question is: what are the differences between these two meds and is my neurologist on the right track? I do like the guy.... seems great. Just feeling like I was reassurance that this med is ok.