If you have an itchy scalp, essential oils of Cedarwood, Patchouli, Rosemary, tea tree, lavender, Peppermint, lemon, benzoin can treat that. Also, maybe try mixing your baking soda with green tea water.
I practice herbal medicine and I make a shampoo bar that has: Saponified Oils of Olive, Coconut, Palm, Safflower and Castor. Aloe Vera Gel, Green Tea, Fresh Lemon, Grapefruit Seed Extract, Vitamin E, Rosemary Extract, Mica, Activated Charcoal, Essential Oils of Lavender, Benzoin Resin, Lemon, Patchouli and Cedarwood.
If you are interested in trying it, you can find it at https://www.etsy.com/listing/125104658/dandruff-psoriasis-antiitch-green-tea?