Are Blister Like Sores Around The Scrapped Area On Elbow Normal?

my 10 year old son fell skined his elbow. Totally normal. we cleaned it with peroxcid and put a band aid on. next thing I notice two days later he has a couple of blisters like soars around the scrap. Now a week later he has more of the blister like spots around the same area, and a couple in other places on his body.....????????what is this

?