Hi Laura!
So after a year and a half your body would definitely be physiologically dependant on codeine even if you’re not actually addicted. There is a difference between the two. So continued codeine use makes your body hypersensitive to pain in order for you to take more pills. When you stop, all your nerves are heightened. Hence the pain you’re now describing. Those physical symptoms last 7-10 days roughly.
Finding non addictive pain relief can be hard and something we all struggle with after giving up codeine. Talk with your GP and explain you’d rather not use codeine and what are your other options.
Best of luck x