My 4 yr old son got a fever 10 days ago that lasted about 4 days. It got up to 103°F. He was over the fever, but had a dry cough . I gave him mucinex and the cough had become productive. Now yesterday, he has gotten a fever again, it stays right between 101 to 102.6..along with loss of appetite , sore throat , headache. I don t know if he still has a virus or an infection? an infection of some kind?