Red dots on arm

can anybody give me a advice what it should be? i've got it on left shoulder for three days and it slowly expanding on whole arm. not itchy.

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Keratosis pilaris, commonly known as “chicken skin,” is the most common cause of bumps on your arms. This condition is characterized by small red or brown bumps that develop on the backs of your upper arms. They may also occur on the backs of your thighs and the buttocks