My son has these pimples on his top right shoulder which seems to be spreading downward. i initially thought it was an insect bite and gave him allergex however it seems to be spreading even quicker now. what could it be? and what can i use for it?

Exam advised: A spreading rash on only one arm raises the concern for shingles. It's uncommon in young children unless they contracted chickenpox before age 1 or if their mother had chickenpox while pregnant. Although there may well be another cause of this rash, I strongly recommend that a physician, pediatrician or dermatologist should examine your child.