Hello, From your description, it looks like you seem to be having a condition called seborrhoeic dermatitis. It is similar to dandruff and occurs on the areas of the body rich in oil glands like scalp, face , chest and back. It is caused by an overgrowth of an yeast which is a normally present on everybody s skin.some people are predisposed to it and hence you have remissions and relapses. When you are having the lesions, you could apply a mild topical corticosteroid. Once the lesions disappear, you could prevent further attacks by using a soap or a shampoo base containing an anti fungal like ketoconazole. Anti allergy tablets provide only symptomatic relief for itching. Hope this helped. Take care and hope you get relief of your symptoms.