Sex (think I might have been used)

Me and this guy started being friends and texting since the beginning of the semester (end of august early September) two days ago he invited me to his room(first time he asked ) .. we had sex. Then the next day I had to text him first and now he won't text me back .. what are your thought ? Do you think the sex was bad ? Did he just use me ? I'm really lost right now thanks .