What could these strange bug bites (??) be?

Lately I have been finding tiny little bites on my hands and feet. The part that makes me wonder if it is a bug bite at all is that I keep noticing one on the same (or damn close) spot on my left thumb. Usually just one or two at a time, but I have noticed them off and on over the last month or so. They are very small, just a bump not much larger than a pinhead. They itch like crazy, but scratching them turns them into little blood blisters. What in the world could be nibbling on me? Might it be something other than a bug bite? Some type of allergic reaction?

Any ideas?