Lily,

The small splotch looks like a bleeding canker. These cankers are often caused by fungi that are weak pathogens. The large splotch looks like sap flux, perhaps associated with a wood boring insect such as ambrosia beetle. Cankers and borers are often indicators that the tree has been weakened and vulnerable due to another stress such as imbalances of light, water, temperature, or nutrition.

By chance, did you add landscape fabric and gravel over the root zone of this tree several years after it was planted? This is what I am gathering from the photos. If so, the tree might be struggling for water or oxygen which is stressing it and making it vulnerable. Ideally, we have nothing covering the root zone or trunk base other than a thin layer of mulch.

There's not much more help I can provide you through the internet. My advice is to contact an extension agent or arborist who services your area and can look closer at the tree in peroson.

Good luck,