My child is 4 years old .He frequently gets cold , sneezing with some less or more mucus.what is reason for it?He is taking bresol syrup now,iron,calcium and magnovit syrup.The problem gets severe in winter.Please tell the solution.Age:4 year,Height :38" ,Weight:13.8 kg,Medical History;good, takes antibiotics treatment when the problem is severe, sometimes becomes healthy with some normal treatment and light medicine.He is healthy , active and has sharp brain.