My 6 yr old son had the flu 2 weeks ago. Now he has a bad cough, vomiting and mild fever. Should I take him to the er? He's been sick too long.?

Take him to his doc. If he is not in respiratory distress - not struggling or working hard to breathe, you can wait to see his pediatrician over the next day. Some children get pneumonia with the flu. He will need to get examined and possibly get a chest xray to determine if this is the case. And then he can be treated. If he is in respiratory distress, take him to the er.