 [ Symptoms ] my 7 year old has been coughing for six weeks and her 5 day z pack did not work what will  she has dark under eye circles is losing weight and sometimes coughs until she vomits [ Disease ] a cough that has lasted that long needs to be assessed by a doctor it could be many things including asthma allergies and even pneumonia or pertussis children should rarely lose weight  this is concerning your child needs to see a doctor right away so she can get on the right treatment plan first one has to consider allergies her cough may be a manifestation of an allergic response those dark circles under her eyes could be allergic shiners  often seen in allergies another possibility would be back to back viral infections    not uncommon with a social girl in school second although uncommon children can get sinusitis with constant post nasal drainage zithromax is not the best medication for sinusitis third we are in the midst of a pertussis whooping cough epidemic even if her cough is not the whooping sound she may need to to be tested