Hi, My 2 1/2 year old son has a runny nose, cough, red and watery eyes and is complaining of a back ache. Are these normal flu symptoms or should I take him to a doctor. He is still eating normally, is not lathargic, but does have a little less energy than usual. This is the first time he has had a cold or flu where he has complained about back pain so I am a little worried. Thanks