I'm really worried about my 5-year-old son. He's been dealing with a chronic cough for the last 3 weeks and usually, it gets better after a couple of weeks with nebulization. Weve been using Duolin for nebulization since he has mild asthma and also using Budecort and Salbair puffs. But this time, there's no major improvement, and his X-ray came back normal. I'm wondering why this could be happening and what else we might be able to do?