My 12 year old son has pus filled little blisters on his right arm. looks like a bacterial infection or maybe insect bite. red around blisters?

? Impetigo: What you describe sounds suspicious for impetigo, a bacterial infection of your skin. You have a tiny break in your skin that you were not even aware of, and the normal skin bacteria could then enter in and cause a local strep infection. The "scabbing" is what makes me especially suspicious. Try washing with antibacterial wash, put on antibiotic ointment, and if not better in a few days, see doc.