I Have Been On Tylenol 3's With Codeine For Almost

I have been on Tylenol 3's with Codeine for almost 5 years. I am female and 66 years old and have acute Fibromalsia. My old doctor just kept prescribing these pills and would do nothing else for me. I decided to get a new doctor who said if I kept taking these pills I would destroy my liver. So I went off of them gradually around the end of October. I have gone 24 days without a pill, but I am still going through withdrawals. It has been terrible. The symptoms I am still having are muscle and bone pain, diarrhea , my nerves are still very agitated, feeling very weak, pain in my stomach, and my heart is just pounding during the day and night, and insomnia. Do you know how long withdrawals take when on Codeine. My doctor said it will take me 8 weeks before I feel better. Is that true? Do you think I should go back to see my doctor about this withdrawal. i just want to be healthy, but I feel just so sick and weak. Any input would be great!!!!!