Just keep baby warm and continue exclusive breastfeeding. If the catarrh is bad, you can do steam inhalation or just add a drop of euclayptus oil on to the cloth or hot water kept in the corner of the room...It will relieve the catarrh....You can also use saline drops into the nostrils. Most catarrh is viral infections which run their course no matter what you do and will go away on their own...all the above are just symptomatic relief treatment...No need to worry. Please try to avoid the risk factors for the catarrh....... No smoking, contact with siblings with cold, no fleeting or cooking in the room, avoid congested overcrowded room etc.......Also try to keep your baby warm and well hydrated.....If persists kindly see a Paediatrician for proper evaluation and management..