According to the site, on June 22, the Keeping Up With the Kardashians star, 31, spent the night drinking heavily at 1Oak nightclub in the Hamptons before entering Southampton Hospital, where he was diagnosed with alcohol poisoning.
All of this happened a day after longtime girlfriend Kourtney Kardashian, who's pregnant with the couple's third child, hosted niece North West's first birthday party back in Calabasas, California.
A source confirms the story to PEOPLE, adding that the reality star – dad to kids Mason, 4½, and Penelope, 2 – is now "doing great."
Earlier this year, both Disick's mother Bonnie and father Jeffrey died, and the losses have left quite an impact on the E! star.
"He's had an unimaginable year losing his parents," the source says. "There have been highs and lows, and he's just doing his best trying to work through everything. He's really making progress."
Reporting by JENNIFER GARCIA