How Can I Treat Dozens Of Painless Red Splotches On My Chest, Stomach, Back, And Arms Over 3 Days?

I have red splotches showing up on my skin over the past three days. It started out as one noticeable one on my chest and has now grown to dozens of them all over my chest/stomach/back/upper arms...but they don’t itch, burn, hurt, or have any dry scaly skin around them. Literally just red splotches. Should I be worried, and what can I do to treat them?