3 more years and you may have more serious issues than just pain from knees and back - like liver and kidney problems. If I were you, I'd think about that first.
For me, I stopped smoking by simply acknowleging that I was hurting my lungs. I was a pre-mature baby, born 3 months early, the surfactin had not been built in my lungs - I nearly died, mu lungs tried sooo hard to keep my body alive, and vice versa...knowing this, I feel sorry for my lungs, and do not torment them with smoke anymore. But it took a very counsious decision to stop.
I do not know what you can do for the withdrawl symptoms, but they will subside, and they will only get worse the longer you stay on the pills.
Maybe seeking an accupuncturist for that pain?