Dr.Jeff
That can be due to a bacterial imbalance on the surface of the skin. That usually results from the loss of the acid and fattyblayers on the skin's surface. Antibacterial soaps are another cause of this and should never be used on the skin.
The skin also reflects the health of the digestive tract, which is another issue relating to the balance of bacterial flora within the digestive tract.
Some people use apple cider vinegar on the skin to restore the acid layer. Good fats on the skin help to create an acid layer.