What Causes Sensation To Pass Bowel Movement During Sexual Intercourse?

hello im 22years old woman. one month ago I had my first sexual intercourse and everytime during this I feel like Im gonna start to bowel movement even I came back from toilet already. Also feels like penis isnt in vagina, feels like it is in rectum, or Im full of gas inside. so to avoid bowel movement I stretch muscles and sexual intercourse-awfull! what is it?

Im healthy, have no additional disease.hope you can help me. Thank you!