Hello...
Thanks for your Query.
Your description is detailed albeit the pics are not top notch.
There appear to be 3 separate issues albeit a common factor like dry skin may link then all and chronic scratching can lead to the darkening and thickening of skin you describe.
However to give you a clear picture and provide a good management plan, more details will be required including medical, personal, family history together with some more clear pics of the affected area.
Next Steps
Online Consultation or an INSTANT Consultation may be worth your while to begin with and will be able to guide you better 🙏
Health Tips
Good Hydration and moisturizer applied atop wet 💦 skin daily especially post 🚿
Good cover with an antihistamine for a few days till the root cause of the itch is isolated.
Treatment of contacts if afflicted is important as is the management of Fomites.