Suggest Remedy For Persistent Red Rash On Arms And Legs

Hello, My 13 month old son has had a petechiael rash on his arms and legs for over two weeks. He also has had a runny nose and cough for a little over one week. He s been more tired than usual but nothing extreme. He is otherwise healthy. Sometimes he feels warmer than usual but I haven t been taking his temperature. Should I take him to see the pediatrician or is it probably just a virus? thank you!