The posts started a couple of days ago, where he posted the following:
The post was worrying enough to fans by itself, but he continued to post similar photos with similarly sad captions:
(This caption is lyrics from The Beatles's "Yer Blues")
This last one is slightly more cheerful:
It's possible he feels overwhelmed by all the negative feedback since his departure from WINNER, but hopefully the messages his fans are sending him helps.
Hopefully he recovers soon.