question: 20  days back my 8 month old son wt 7.7 kg got cough and cold , doctor prescribed kufril , nasoclear and duolin respules for nebulisation and azithral liquid . He got cured within week .yesterday night he got fever  and i gave p-250 2.5 ml and today morning he was very active and i continued p-250 but now he got cold he is taking feeds well. Again cold whats the reason