Anal sex pain...

I've tried anal sex a few times now with different men and my experiences have been kinda bad. The first guy wasn't that large and I thought that would make it easier but it still hurt like hell and I stopped him after a few pumps. Second guy had a huge member and before he even got the head in I was like, "nah." Last night I tried with my boyfriend and we used lube I was calm and it felt great. There was moments of slight pain but overall very good. I even got really close to cumming from it. This morning however, my butt hurts so bad. I'm pooping all loosely and it kinda burns. Should I be worried? Is this normal? It technically was the first time I went all the way through with it.