Reply to neck & back solution
Mike, it sounds as if your bike is not set up correctly.
I'm not far from your age and rode competitively all my life. Then I had a seven year lay off. Since last year July I started riding again and after one year of hard training, I'm now starting to get my form back. When I started riding again I had exactly the same problem, as I lost all my suppleness and using my old faithful bike, I ended up with severe back pain and neck soreness. Changing my set up on the bike helped some and doing extensive stretching exercises, fixed all the other problems. The latter took a bit of time though, but now I'm back to my favourate riding position, with now more problems. I have to keep up with the stretching exercises though, otherwise the back pain comes back a little.
Suggest you have someone experienced check out your position on the bike.