My boyfriend has some red spots on his back and he says it's very itchy. but it's only on his back. is it chicken pox?

Chickenpox Rash: A rash from chickenpox often occurs first on trunk (chest/back) ; then moves to face ; then extremities. The rash becomes blisters that itch. Blisters usually have all transformed into scabs in about a week. There are usually around 100 to 300 lesions (more on adults than small children). The rash could spread to mouth, eyelids ; genitalia.