I wonder if the smiley pill is a metaphor for Jaeyoung's happy emotions "fizzling out", consumed by something that drowned them, rather than him being drugged at some point. Could be both as well.
I love Seungmin currently. It's clear he has quite the high affection for Jaeyoung, and I really wonder why and when and how this happened. Could've started from his voice, or as a previous fan of the group. Regardless, I hope the reason and outcome of his feelings won't cause Jaeyoung any further grief and that he can actually help him heal from what happened that drowned his emotions.