Those sure look like chicken pox......all five of my kids had them at one time or another.
That being said, your son doesn't have all the symptoms that go along with this infection...but, everyone is different.
Here is a very good article from a highly respected source you might find helpful:
So. What should you do?
Take your son to the pediatrician tomorrow so as to get a definitive diagnosis.
There is no specific therapy needed at home at this time.
Does this make sense to you?
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Dr. Rick MD FACS