As James said, you should not be experiencing any pain from hepatitis C. Certainty not moderate to severe pain.
Do you know what stage your liver disease is? (Have you had a liver biopsy?)
First, you should find a doctor who can determine what is causing your chronic pain. Then hopefully they can treat the source of your pain rather than masking the pain with an opiate. Since your current doctor(s) have not done this, I would seek a second or third opinion until you find someone to help you.
Second, if the source of your pain can be managed or eliminated then you can proceed with stopping the morphine. Morphine is an opiate pain killer that can be highly addictive. You should get help weaning yourself off of the drug. Coming off of the morphine will be difficult after 3 years of use. I would seek help from a doctor that specializes in drug addiction or find a pain clinic at a hospital that is experienced weaning patients off of addictive drugs.
You may want to post your questions regarding opiate addiction in the MedHelp Addition-Alcohol-Drug-Rehab Community
I am sorry you are suffering with pain and hope a doctor can determine the underlying cause and give you some relief.
Perhaps after taking care of your current issues you will then want to proceed to treat your hepatitis C.
Good luck to you.