I've Been Working In My Father's Garage (which Is Not

I've been working in my father's garage (which is not the cleanest) for the past few days on an art project and just today, I noticed three crater-like wounds on my right bicep. They are 1mm in diameter and look much too large for an insect to have created them. Two of the three wounds are placed about a centimeter apart, giving the illusion of a fanged bite, though, the third wound does not have a visibly distinctive double. The first few layers of the skin seem to be torn from the wound with a pinpoint incision in the center (one is red-pink, the others are barely visible). What are these wounds and should I be concerned?