Could this be Chicken Pox? Again?

Anyone in the mood to play doctor? Any childhood disease specialists hanging around? Want to take a look at my son?

EXHIBIT A
My 12 year old son is in the middle of experiencing this:

"The first signs of chickenpox are usually a slight fever and a general feeling of illness. Within a few hours or days, small red spots begin to appear on the scalp, neck, or upper half of the body. About twelve to twenty-four hours later, these spots become itchy and develop into fluid-filled bumps. These bumps, called vesicles, go through a series of changes. First they turn into blisters. Then they break open, and scabs begin to form on top of them. This process goes on for a period of two to five days." (from http://www.faqs.org/health/Sick-V1/Chickenpox.html)

And he looks like this:
EXHIBIT B
Not too many spots, I'll grant you. It shouldn't be chicken pox, since Timothy has had the varicella vaccination. He's also experienced this exact same whatever-it-is once before. At that time, our doctor's office said that they couldn't be positive what virus he had without running tests, but they thought it was chicken pox. Apparently the vaccine is only effective 75-80% of the time.

What is more convincing to me, however, is the comparison between the following picture of one of Timothy's blisters, and the picture on this webpage.

EXHIBIT CWhat do you think? Should I be warning parents around me and canceling long-awaited sleepovers?