17, female. tiny pin point red dots about 30 scattered on arms. noticeable only when i carefully see it. cbc in november was normal. concerning?

Not particularly: Without looking at it it is hard to say for sure. However, any dots that show up on such a localized area are most likely a response to some contact material. Creams, lotions or soaps that came in contact may trigger a local rash. Sometime if you cough hard or throw up you can trigger such dots in skin above your heart (head, shoulders, arms). I can't think of a bad source.