Thank you for your query on Healthcare Magic.
His runny nose and eyes with crust in eyes caused by conjunctivitis
of the eyes and a common cold
caused by a virus most probably.
Some times conjunctivitis of eyes leads to excessive water discharge leads to runny nose as the water from the eyes are drained into the nose through the lacrymal system of drainage
It is not related to his teething
Teething will cause gums irritation and not associated with loose stools or cold and conjunctivitis as many people think.
For his symptoms you can give an oral antihistamine like cetirizine
in prescribed dosage and for eyes if there is any secondary bacterial infection, antibiotic eye drops can be given.
Therefore I advise you to consult your doctor for the examination and for the prescription of medication.
Hope I have answered your query.