In regards to the neck, I am so happy for you!!!!! That is great news.
As to the lower back, every doctor that I have seen tells me, walk, walk, walk, even if it hurts. It will hurt you more in the long run if you don't. Try gentle stretches and even if walking involves a short walk around the dinner table, or around your yard ( if you don't live in the Northern states right now where it is 50 below), then that is okay too. Any amount of walking is better than none. I have lower back pain and I force myself to walk, even while cursing the entire time. I got myself a dog to force myself to walk.
About 80% of everyone will experience back problems in their lives and most of them resolve themselves in time with proper care. Something as simple as walking and stretching could do the trick. I also suggest a hot soak in the tub. Works wonders for me.