I just started using the New Head & Shoulders intensive solutions for severe dandruff prevention and seborrheic dermatitis (Dark blue bottle) and it works really good. I am about 90% free of scalp build up and flakes. And my hair doesn’t seem as dried out, but I also use a good conditioner just in case. I am also taking a multivitamin and biotin everyday.
Because you said that you had white/yellow scabs, you could have seborrheic dermatitis.
I use Organic Apple Cider Vinegar (Bragg's) for my seborrheic dermatitis and sensitive scalp. I typically take about 1/4 cup of Apple Cider Vinegar and 1/4 cup of water and mix it in a spray bottle (1 part to 1 part). I spray it directly on my scalp, by combing through the different sections. Then leave it on for at least 10-15 minutes. Then I rinse it out and use a mild shampoo & conditioner. The longer the better. Its best to do it on the weekends or at night because it does smell. (2-3 times a week) The worse you have it the longer it will take to see results. I started using the ACV because the Nizoral shampoo started making my hair really dry and brittle and it started to break and fall out. I have pretty oily skin and I needed to wash my hair every day. For the face, take a cotton ball and dab the mixture on the spots.