Hey! You can use castor oil with little amount of coconut oil. It will make your scalp good and will strengthen your hair too..

Everyone has given you great advice... make sure you get that appointment with the doctor! In the meantime, have you tried a sulfate-free shampoo? I used regular sulfate shampoos for my whole life, but a few years ago, they started making my scalp dry and itchy. I would get little scabby bumps which were actually just sebum buildup (sebum is the natural oil produced by your skin), but if I scratched them, them would get weepy because I'd sort of unblock the pore and a bunch of sebum would come out. If I scratched too much, they would bleed. I tried many things, from washing more to washing less, using cleansing conditioners, and using sulfate-free shampoos. Ultimately, I found that the cleansing conditioners made my scalp the happiest, but they didn't get my hair clean enough, although they are amazing for maintaining hair color. So now I'm using a tea tree oil sulfate-free shampoo and I wash every few days. I make sure I wash my scalp really well and no longer have the itchies or flakes.

The suggestion of using coconut oil is a good one, too. Every now and then I do a deep "soak" with coconut oil on my scalp and hair. It makes it feel amazing. I would recommend exfoliating your scalp first with some brown sugar mixed with conditioner and then applying the oil. That will help get rid of excess flaky skin before you moisturize. However, if you find it doesn't help, then your problem is likely not moisture but instead fungal or a skin disorder. Henna is also good for soothing an irritated scalp, but it dyes your hair red (although you can pair it with indigo to get black). Cassia is a henna alternative that doesn't dye your hair unless it's white, but I'm not sure if it has the same properties.