Spots on your back may often be attributed to different causes such as allergy, skin infection, or a burn. If they cause itching and they are gone in the morning, it probably is a symptom of sensitivity or potential skin problem. To control it, always wear clean clothes and use a light hydrating cream. If, in case, the situation is continuous or worsens, get a dermatologist's consultation. They can help you with the right diagnosis and proper treatment. Take care of your skin and be hopeful!