I think the protein drink that was given to Kim Dan that was meant for Jaekyung had Molly/MDMA/Ecstasy in it. Probably with the intention of getting Jaekyung to fail a drug test and to get disqualified. Molly apparently makes people really lovey, horny, and cuddly as well as illogical or disorganized thoughts, hot flashes, and intense sweating (basically everything that Kim Dan is going through).
I could be wrong, and this turns out to be a yoai magic horny drink or something, but I’m pretty sure he was drugged.