Why has your Yoshimo Cherry Tree sudenly started leaking thick sap clusters from trunk and branches What causes this?

leaking sap is for a cherry tree like a fever for a child, meaning its a general sign something is wrong but not enough to know what. is the tree old? is it getting enough fertilizer and water? do you see sawdust on the ground? do you see a sparkeling dew like drops on the leaves? do you see any insects? anything else which wasnt there before?