I have a really dry scalp that wont go away with dandruff shampoo, how do I get rid of it?

Seborrhea. You probably have seborrheic dermatitis; I'm an expert on that, because I have it too. Over-the-counter dandruff shampoos work on mild cases, but for more serious dryness you need a prescription shampoo such as loprox (ciclopirox) or clobex (there are many others). I often add an anti-inflammatory foam like Luxiq or olux, which can be aplied directly to the scalp and won't mess up your hair.
Seborrhea. Seborrheic dermatitis is thought to be due to a combination of an over production of skin oil and irritation from yeast. Seborrheic dermatitis appears to run in families. Stress, fatigue, weather extremes, oily skin, infrequent shampoos or skin cleaning, use of lotions that contain alcohol, skin disorders (such as acne), or obesity may increase the risk.

Related Questions

What's a cheap way to get rid of dandruff, besides dandruff shampoo?

Wash hair frequently. Try tar shampoo followed by a cream rinse or lemon based conditioner. This remedy might not be as effective as using an anti-dandruff shampoo because these contain antifungal ingredients that kill the fungus (malassezia) that is associated with dandruff.