Just put it in a water bowl. Mine drink it down just fine. Did you find a place? Sometimes large grocery stores, drugstores, supplement stores, health food stores . . . .
He may have gotten into something toxic.
At the very least I would give him some food grade activated charcoal supplement.
https://www.backyardchickens.com/t/700526/flushes-for-aiding-in-toxin-removal#post_9508213
This link includes flushes - to get him to pass what is in his digestive...