You need a complete evaluation for your rash since they have been persisting since 2 years. A clinical examination is very important for diagnosis. Based on information shared by you the few possibilities are dermatitis herpetiformis, pityriasis rosea, and psoriasis.In dermatitis herpetiformis there is itchy rash with red bumps and blisters associated with sensitivity to gluten. White scaly rash over red irritated skin could be due to psoriasis. Scaly red rashes with slight itching are seen in Pityriasis rosea.Get yourself assessed by an expert dermatologist. Treatment will depend on the cause.
Take care and best regards!