coughing and fever in child ?

OK, my son (7 yrs) has been running a fever of and on from 100 degrees to 104 degrees, coughing (productive) and can't really keep any food down. He throws up most of what he eats. He acts fine, playing around (right now he is beating up daddy) No aches or pains anywhere. He hasn't lost his appetite at all. We took him to the doc and he said "We're gonna treat it as Bronchitis." So he wrote him a prescription for Penicillin. This has been going on for a week now.

I just don't believe that this is Bronchitis. The only symptoms he has are fever and coughing (with mucus.)

See below:

Symptoms may include, a dry cough that will entail mucus being brought up out of the lungs, headache, chills, fever, soreness or tightness in the chest, wheezing and problems breathing. Children with this infection are more susceptible to other infections. Children with asthma, or who are victims of secondhand smoke, are more susceptible to a bronchitis infection.

I have looked in all the medical books we own and I have tried to research online, but I can't find anything with his exact symptoms. Does anyone have an idea of what this might be? And ideas will help!

PS- I know it's not "just a cold" because when my son gets a cold he just lays around all day. He is still very active.