is this a bad sign? what should I do?

during the school year this guy stared at me constantly, checked me out, and by was all of my Instagram pictures. he was still liking my Instagram pics into the summer. I added him on snapchat a couple days after school ended and he added me back and snapchatted me that night a video of him that he also posted to his story. I didn't know whether or not to respond so the next day I did the same thing (sent him a pic that I also posted to my story). he opened it and hasn't snapchatted me, and I've posted 2 pics on Instagram since then which he didn't like (and I know he saw them). has he lost interest in the past 3 days? why did he go from snapchatting me to not liking my pictures? if I give him time is it likely he'll do something or is he done with me?