The child caught a cold and shed tears.

This situation is likely to be caused by infection nasolacrimal duct blockage, dacryocystitis. Tears produced by the eyes will generally flow down through the nasolacrimal duct, if the nasolacrimal duct blockage, tears can not be discharged, children will continue to flow tears. In this case, parents can first give erythromycin eye drops to control infection.