10 year old boy with rash on back, chest and upper extremities. possibly chickenpox. no fever?

Sounds odd for cpx: Chickenpox usually emerges on the face & neck before spreading. The lesions start as a small bump that changes through a blister that mimics a dewdrop on a rose petal. The lesion breaks & drys the same day. New spots come in crops for several days. If truly cpx he was contagious from the day before the rash & a week after. Keep it clean It it passes. If not cpx it could be several things.