Cold congestion dry cough. Medications.

13 days before my 19 month old son got running nose and mild cough and later he got fever with temperature 100.3 immediately I gave p125 syrup 3 ml and the fever got cured.later he got developed with thick mucus and very sticky thick dirt in his nose I didn't give any medications other than nasal drops till now. We are currently staying in Chennai and went to blore.he got cold after we returned from bangalore and it is second time he s getting cold when we returned from bangalore. Now he is suffering with Little dry cough mostly while sleeping and mild congestion nd he is asking water by coughing and drinking more water whenever he s coughing. Please suggest is this Normal or he needs medications.