Red Acne-Like Bumps on Toddler Legs

Does anyone know what these are? (They look a bit more irritated than usual because my toddler has been picking at them when he sees them but they don’t seem to be ichy or bother him) They fee very risen similar to pimples and have been there for 5 days with no indication that they are getting better. he has had them before on his arm but not as bad (maybe one or two). They eventually went away but i just wanted to make sure that it’s not cause for concern.

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