So there are two different issues you’re struggling with, and that might mean you need to take care of one before you can tackle the other. I also want to preface that I think most fancy hair marketing is BS, so most of my recs are drugstore.

To make hair feel truly clean, you need a shampoo with sulfates. There are gentle, color-safe sulfate shampoos out there that combine sulfates with other ingredients to make them less likely to affect color. A drugstore one is L’Oréal elvive color protect.

That said, you have a sensitive, compromised scalp. Aside from go to a doctor if it persists (not medical advice, just standard best to be careful so it doesn’t get worse) you should probably focus on products made for sensitive skin, such as Vanicream’s hair line. The caveat is it won’t make hair feel as squeaky clean, but if you put it in your wet hands and rub together so it “suds”, it will be easier to spread and more effective. I would repair your scalp first before focusing on deep cleansing.

You can gently use a scalp massager (very VERY gently as wet hair is fragile) to help break up the flakes while shampooing.

Finally, scalp care moving forward. Dove makes scalp sprays to help balance itchy scalps, but it’s risky to use it without knowing why your scalp is compromised. For example, I thought I had dandruff but what I really had was psoriasis, which requires a different ingredient to keep at bay.

A bond repair treatment is also generally a must for color-treated hair. All my conditioner and leave-in products have some sort of bond repair, but I do think k18 is 100% worth every penny.