I'm sorry to hear about your pain. My mother has stage III pancreatic cancer and she had considerable pain for quite some time. I don't know if this will help you, but my mom got two shots for the pain. From my understanding, they literally stuck some kind of tube down her throat and into and through her stomach and then injected something into her. I'm not sure whether it was the tumor or the nerve, however. On her first attempt, the shot did not work very well, but it did on the second. She has no pain associated with the tumor any more. Hope this helps and I wish you all the best.
If you would like more info, please ask me and I will ask her exactly what type of shot she got.