J.O.
It could be seasonal allergies. Our pediatrician put my 1 year old son on an allergy medicine (after a round of antibiotics failed to get him better) and he is doing much better. This is the worse allergy season on record and even people who don't typically react to outdoor allergens are having trouble. I was reluctant at first to start the allergy med, but he had runny nose (clear mucus) and a cough for over a month. His symptoms were worse at night and early in the morning. It may be teething, but if it persists for too much longer, I would talk to the pediatrician.