Is what the questioner saw in his dream, and the burning sensation he felt in his anus upon waking, the work of Satan, especially since it occurred late at night?

A dream is of three types: glad tidings from Allah, a narration from the self, and a fright from Satan. What you saw may be among the things by which Satan grieves the son of Adam. What one should do if they see something they dislike in their dream has already been explained.