From the description given by you there are a few possibilities. It could be eczema, intertrigo,
dermatitis, impetigo, lichen planus or
psoriasis. Dermatitis is usually caused by allergens causing redness swelling and blisters. It happens in response to allergens. Eczema can affect neck, knees, and elbows and causes oozing, bleeding blisters and thick patches caused by climate, allergens and illness.