Hi there
I hate to say this but it really could be anything. The fact that they are spreading is an important factor. This is something that you really need to see a doctor or a dermatologist for because even if you figured out what it was...you will need treatment. I hope that by now it has gone away or you have sought medical treatment.
In the meantime here is an article about what to do when you have an unexplained rash.
Hope you are feeling better by now. Thank you for your question.
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