Since your baby in exclusively breast feeding age continue feeding the baby....Breast milk offers extra protection from cold-causing germs...try saline nose drops to loosen thick nasal mucus. Look for these over-the-counter drops in your local pharmacy...Running a humidifier in your baby's room can help improve runny nose and nasal congestion symptoms. Aim the mist away from your baby's crib to keep the bedding from becoming damp....Consult nearest pediatrician for examination and for specific treatment Regards.