Should I be concerned?

Hi! My son has two red marks on his outer thigh and I’m just wondering if it’s worth a trip to the pediatrician. Has anyone experienced this before? At first I thought it was a reaction to his 6 mo vaccines, but it’s not going away and showed up in two places. Sometimes it’s more red than other times. I tried the google machine, and it doesn’t *seem* like ringworm because it’s not raised around the edges. But maybe it is? Could it be eczema? Thoughts?