Hello. I Am Concerned About My Mini Poodle. He Is

Hello. I am concerned about my mini poodle. He is almost 14 years old. On Friday he tried to use the bathroom but couldn't. When I checked him later I saw that he did use it but it did not fall to the ground. I washed the area and discover that his rectum was swollen. It is still swollen and it seems that there is a discharge. Please tell me what is wrong with my baby. Thanks