first time doing anal and...

So I did anal for the first time today and it hurt at first. But as my boyfriend was going in it kept feeling like I was shitting and even when he was thrusting it kept feeling like I was shitting. When will this feeling going away or does anal always feel like that? And omg the worst part is my boyfriend came in my ass and it didn't drip out..kinda thought that was weird then an hour or two later I had to go to the bathroom really bad and I thought I was going to shit but when I shit, I was shitting out his cum!!! Every time I've gone to the bathroom since then I've been shitting out his cum and no poop! Just cum! This is so weird...is this normal? And when I was sneezing it squirted out cum onto my underwear by my vagina. Is there anyway I could get pregnant this way? And why the hell did my ass hold up all the cum and shit it out ???