Should I be concerned about my son?

My little man was diagnosed with staph two weeks ago and ended up with a few sores next to his mouth and one on his leg. He was put on antibiotics and was supposed to take them for 10 days but I forgot which day I started so when they started to look better I stopped it probably 7 or 8 days in. Im worried though because those spots where his sores were aren’t going away. Should I be worried or do you think they would go away eventually?