After anal

I just had anal with my boyfriend. And he did cum in my butt. I did not go to the bathroom directly after. I waited about an hour (to go to my own house) to try to “fart the cum out” Bc I read it prevents getting the shits. Well when I did try this [[TMI]] I farted out watery poop. Do you think this got on his dick also? And why am I farting this out but not the cum ?