7 mo. ago I started using Retin A on face & neck. I started with .025 strength cream once a week, finally worked up to nightly use. 3 mo. ago I started using .05 strength using the same gradual frequency increase. With this strength, my neck lines got very itchy and deep red in color. It cleared up when I stopped use on my neck. (One of the lines on my neck has a scar). I've gotten minor improvement of the fine lines on my face, no improvement of my neck. Do I need stronger nightly use?