Why does it hurt??

Last night I had sex in about a month or so. It was going great until he came, he came inside me & we waited like 20min before we had sex again. But the 2nd time he went in it hurt soooooo bad!!! Like I wanted to cry cause it was very painful & it literally felt like my whole vagina was ripping apart! Is that normal??! I've never experienced this pain before but yesterday it was too much :( what can it be?