Suggest Medication For Small Red Bump Like Rashes On Inner Thigh Of A 2year Old

My 2 year old son has a rash only on his inner thighs (outside of his diaper). We think it came from him over wetting his diaper one nights don t waking up from it, so it sailed his pjs. Last night he was wet again and it got more red. He has small raised bumps that are red in color. I have washed him good right away and but diaper cream on it after. What should we do?