K.L.
Relax. Keep cool. Assure him that this is all a part of becoming a big boy, and that he's doing great. Tell him that soon he will be using the potty every time, and let him know that the whole process is easy and fun.
Meanwhile, keep an eye on stress in his life and in yours. Are you tense? Is he too busy? Are you too busy? Anything you can do to bring peace into your lives will help him to focus on this new skill he's developing.