I had something similar when I was in FNQ - I think it was a heat rash or a reaction to the sunscreen I was using. Are you using a moisturiser or sunscreen there at all?
I got something like that from a vaccination reaction - MMR I think. Have you had any vaccinations in the last month? Otherwise a virus although it is lasting a while. You could take a hay fever tablet like claratyne to see if that helps with the antihistamine. Don't worry about the fact that the dr can't see it as they can always feel it and that might be a key symptom - you never know!
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