+1
I have eczema, dry skin, and allergic ingredient issues. My general solution is to (1) eliminate irritants (ingredients and rubbing /scrubbing) and (2) hydrate scalp with good water. If steps 1 & 2 are not enough, then use skin soothing / moisture sealing / medicated / home remedy ingredients. I imagine you know quite a bit about scalp issues by now, so please don't be offended if my comments seem obvious.
My fav itch routine:
--
Stop the itch - 5 min ACV scalp soak pre-shower (applied directly to scalp with fingertips or spritzer, once a week, as needed)
--
Scalp-only wash -
CeraVe Hydrating Cleanser (a gentle cowash), sometimes medicated poo
--
Hydrate - Hydrate skin for at least 5 min (daily if possible and helpful). Carbon and fiber on-the-nozzle shower
filter removes irritants, whole family less itchy.
--
Condition - with low-irritant conditioner
--
Seal in moisture / calm skin (when having bad itchy dry scalp issues) - apply cortisone alone or mixed with low-irritant lotion or oil to scalp within 3 minutes of getting out of the shower
--
Drink more water
Now that the humidity is high, I can skip the cortisone / sealing, wash less, and do almost no home remedy / medicated stuff.
To seal IN moisture and sooth the skin, the skin must first be fully hydrated by being in the shower or bath for at least 5-10 minutes, then apply oil / lotion seal. Getting the scalp wet (dry hair, outside the shower) with wet fingers or a spritzer gives some relief, but not as good as washing, hydrating, then sealing. Applying oil to dry skin seals moisture OUT. Washing (removing oils) and not sealing afterward dries out skin.
http://www.easeeczema.org/ helped me learn more about dry skin. Safflower and sunflower oil are two of the least irritating and non-comedagenic oils. Some oils and lotions will clog pores and irritate skin - more on
http://www.zerozits.com/Articles/acnedetect.htm#inglist . I have made small batches of lotion (less than a weeks worth because no preservatives added) by mixing equal parts oil, glycerin, and aloe. I also like Kiss My Face seriously sensitive fragrance free lotion and have heard great stuff about CeraVe.
It is a good idea to do a patch test on every product to test for ingredient sensitivities (sensitivities can be worsened by dry air and other skin / health conditions). Tea tree and other herbs can be very helpful, but any "treatment" can also be irritating.
For some skin conditions, it may help to use a SLS / SLES shampoo to clear out the pores without irritating the skin by massaging (massaging is necessary for low/no poos). Using SLS / SLES medicated shampoos can be great to treat skin conditions, clear off irritating residue, clear out pores, and stop the itch cycle; but they can remove the protective oil barrier, leading to dry skin. You can replace the protective barrier with non-irritating lotion, oil, or conditioner. For medicated shampoos, I like
DERMAdoctor Born To Be Mild Medicated Face & Body Cleanser (fav, no sticky shampoo residue, less oil stripping, fragrance free), T-sal (2nd fav, fragrance free), and T-gel (3rd fav). A fragrance free, no frills lowpoo such as Free&Clear Shampoo might be good to rotate in and less oil stripping. Free&Clear Co is fragrance-free, no frills (= fewer ingredients to be irritated by), can add safflower or sunflower oil to small batch. Jessicurl, Kinky Curly Tiny Twirls, and Spiral Solutions on Etsy.com, Cure Care at Sally's, etc. come in fragrance free (though fragrance may not be your issue), but may have other irritating ingredients. Medication / home remedies can be added to a no-frills non-irritating routine. It helps to rotate products / routine.
Good luck!