I have a rash at the back of my neck with burning and itching. any idea. ?

Rash on neck: When allergens are present in clothing or bedding, they can affect the neck and cause an itchy rash. Common allergies that cause neck rashes include soaps and detergents that have been used in the laundry. Mild allergic reactions typically disappear within days and are prevented by changing laundry detergent brands. If there is pain shingles is a possibility.