1 yo is having red, sore bottom because frequent stools. What should I do?

Anne
My 1 yo is having red, sore, thick skin around his anus & scrotum which is painful to touch due to frequent stools per day (not diarrhea). 
I'm currently not wearing him any diapers and use baby powder (pure cornstarch) everytime I change his pants.
Am I doing it right? I feel so so sorry for him.