My Two Year Old Son Had Lidocaine Injection For Stitches.

My two year old son had lidocaine injection for stitches. The opposite side of his face now has small reddish spots. They are very small like tiny freckles. They travel down his face basically down the blood vessel path. He is not running a fever and shows no signs of ch for?feeling bad. He was back to running around like crazy after he got the stitches. Do I need to rush him back to emergency room? Should I take him to pediatrician in the morning? Or just watch to see if it goes away? What causes the red spot side effect from the shot? What do I need to eat