Welcome to the board. I'm sorry you are having so much pain as a result of your procedure.
Please elaborate on why you had the rhizotomy done (why is the nerve or nerves compressed?), at what level it was done, and are you to have a follow-up procedure?
Are you using ice for pain? I've found that when opioids do not touch pain, ice will help. You can ice for 15-20 minutes per hour, round the clock if needed, being careful to protect the skin.