Hi I Have A 4 Year Old Son And I

Hi I have a 4 year old son and I had my mother watch him today but I had to come home because he was to bad and is always wound up and mean but I started to spend him on his behind n found that he had been in his room with his coloring stuff out and had those short little kid markers and he had markings all over his butt and completely covering the rectum hole and have often caught him playing with himself and he has never before seen any of the things that he isdoing and I ddon't know how to deal with him or with what he has been doing please help me