Q.Small peaches shriveling…
Tree looks healthy and putting on new growth. Some scattered peaches are the size of golf balls, but many little ones (the size of your pinkie) are shriveling and sickly looking. They even have odd shapes.
Your tree could be suffering from a brown rot fungus.
You can treat most fungal disease with a fungicide.
Have you had heavy rain or wet conditions in your area?
Here is a few links for you.