Codeine addiction

I have Osteoporosis and Neuropathy but my GP does not want me on pain meds...I am currently on 150mg Codeine....I did try Lyrica but had a dreadful reaction the Codeine suits me but Doc does not want me on it
.I have tried several times to quit but get too many pains in my legs to keep it up...what is the ACTUAL TIME involved for a withdrawal of 150mg Codeine is it days or weeks...the physical time not the follow up.