The Fentanyl is a strong medication and while it works great for some it may
not be the medicine for you. Are you taking a break through
medication with it?
Talk with your doctor and explain that it is not working and see what other options are available for you to try.
All of us has been through this. It is very frustrating but once you find the right medications it will have been worth it.
Your metabolism has a lot to do with how well a medication may or may not work for you.