My son has his chicken pox vaccine 2 weeks ago..last week the spot around where it was injected got really red and went away within a few days. Now last night red spots started appearing all over his chest, stomach, back, neck, and butt. His butt is now covered in blisters, and the spots around his body spreading a little (now he has a few on his face) and the ones around his body are getting more red. Could he have chickenpox after getting the vaccine?