I have SD too and it's awful! I feel your pain.
I've found using products with Tea Tree Oil or Peppermint work the best. My hair loves protein so I'm using Giovanni Tea Tree Triple Treat Shampoo and Conditioner. These have been wonderful. I also have a bottle of tea tree oil from Whole Foods and will add it to the conditioners I use on my co-wash days.
Like the others mentioned, brown sugar in your conditioner will also help immensely. It's such a great, natural exfoliant. Coconut oil also helps. I will use it as a deep treatment on the weekends.
If you have issues with SD in other areas, you can use a dandruff shampoo as a wash. My dermatologist recommended I use Nizoral for the SD on my face. It was the best advice ever! Be gentle near the eyes though. My flare-ups have lessened since doing this.
Fat Thumbs + iPhone = Errors