So I've itchy for 20+ years. The best thing i've found is giving my self a "skin bath" using a natural bristle fibre long handled brush at least one before going to sleep. I find when changing clothes and getting a chill really affects me. Mostly on my back but at any one time i could probably notice 15-20 spots on my body simultaneously itchy. Like right now. This a like a lymphatic massage so work from your feet to your heart and then head down towards lymph nodes.
Feels divine. better than any ordinary back srcatcher! or trying to direct your partner who never gets the right spot! haha. Or cream.
Try it and let me know how you go.