When you say as it gets removed, what do you mean removed, do you remove it yourself? If so that may be a reason for the dry, itchy rough character as self-removal of skin is traumatic to your dermis and epidermis and may cause further irritation. As for the causes of Seborrheic Dermatitis, unfortunately the health community had not found a definitive single cause to the symptoms, rather it seems to be a conglomeration of aspects which yield its presentation. Common connections and potentiates include stress, genes, certain medical conditions and medicines, cold, and dry weather. You may look into purchasing humidifiers to keep your skin moist, as well as to maintain adequate hydration to ensure none of your organs (your skin is an organ!) are dehydrated. As such I would assess and document your lifestyle regimen including medications, diet and creams and bring these to a dermatologist to ask for a definitive answer. Describe the history, your symptoms, and everything you ve attempted. Being a specialist and seeing such conditions commonly, I believe they may have the best and most specific answer you may be looking for. I hope you experience relief! Warm Regards.