I'm stressed

Sssooooo.... Me and this guy have been talking HEAVY since my bday in July... I was thinking he was really into me and I was starting to like him.. But out of nowhere he pumped the breaks.. We talk less frequently.. AND he posted a vid of him and some chick on his snapchat... Never wants to chill always claim busy.. I was really starting to feel him.. But then this happened... What should I do?