My girl also "on and off" coughed for more than a month. We gave her different kinds of cough syrup, soup, and herbal formulas, and nothing works for her. Lastly we brought her to the doc, and found out she got bronchitis. Doc told us this is caused by long-term coughing. Better to send your kid to the doc. The longer she coughs, the easier she will have bronchitis, which eventually become asthma.