After a month of sunburn i noticed that i have white spots on my arms and body.some are large and without shape it does not itch.what can i do?

Skin changes: It sounds like you need to visit a dermatologist. There is a possibility that you may have Tinea versicolor, which is a non-contagious fungus which causes light or dark circles which may coalesce into larger areas. It is important to wear sunscreen and avoid sunburn. Sun damage can lead to serious skin conditions including skin cancer. Remember to protect yourself from the sun.