I'm really worried about my 5-year-old. He's got these prominent bronchovascular markings, and his ESR is at 13. Is this serious? He's been coughing non-stop and always seems to have a fever. His recent blood test shows an absolute lymphocyte count of 5500 and a monocyte count of 9. We've been giving him normal flu medicines and using a nebulizer, but it doesn't seem to be helping. Could it be some kind of allergy?