The pattern you describe is typical of children who are on the verge of accomplishing toilet training but who are either fearful around use of the potty or reluctant to 'give up' their young behavior. Accomplishing toilet training brings with it some ambivalence - while it is a sign of growth and development, which is inviting to most children, it is also a sign of giving up some of the
dependenceAlcoholism
Chemical dependence - resources
Drug abuse and dependence that is inherent in being a small child. The latter is not so easy for some children. What does your son say about the situation? Does he indicate in any way that he is interested in accomplishing this task? What feedback do you receive from him?