I Have Several Small Blister Like Sores. They Start As

I have several small blister like sores. They start as a blister that itches but once it pops no longer itches. It turns into a round sore that looks like a cigarette burn. From beginning to end happens within a few hours. I have one on my upper abdomen, two on my hand, one behind my knee and one on my shoulder. The sores do not hurt nor itch. It almost looks like ringworm but small and no itching.