What Causes Appearance Of Skin Coloured Bumps Above Foot In Infants?

Hello, my son is 2.9 years old and just received his MMR and Chicken Pox vaccine 4 days ago. I noticed that he developed three little bumps above his foot (around the ankle area). The bumps are not red or white or itchy. They are the same color of his skin and they are in the shape of a triangle. He has also had a change in his bowel movements. Should I be concerned or could these symptoms just be a reaction to the vaccines? Thank you!