Toddler has pimples on knees goes down to feet

Before was about to change his diaper before bed, i took off his pants and noticed these on his knees and feet, the legs is rarely there the pimples but its more visible on knees and feet. Im going to take him to the doctors tomorrow because we already have appointments and at least his doctor can take a look at it. But wanna know if anyones toddler had gone through the same or something, thank you!