I am willing to bet that this is just from the way you are sleeping. If you sleep very soundly and on your left side, you may simply be compressing the cartilage in your ear against the bed or against the pillow and this could be leading to soreness, especially if it tends to go away over the course of the day. If this is the case, you may want to try sleeping on your back or on your other side to see if that makes a difference.
Otherwise, I can't think of many common causes of ear pain
. If you notice anything unusual about the skin on the ear, such as a rash, a warm or red spot, or any blue discoloration, you should immediately mention those to your doctor
. Also, if you notice that any other parts of your body are randomly painful or discolored blue, especially your fingers and toes or tip of your nose, then you should mention that as well, as these together may be signs of a circulatory problem. Again, however, I think a serious problem is unlikely.
However, please consider getting in to see your primary care doctor
who can take a look at it for you. Better safe than sorry!