I ate it.
You XiaoMo feels someone supporting him. He only manages to catch a glimpse of Ling Xiao before losing consciousness.
Soul force overuse? One look and Ling Xiao can see that there is a problem with You XiaoMo's condition. He frowns. He is not that well versed with mages and their practices. But he knows that usually a mage is able to tell how much soul force he has left when refining magic pills. So, most mages, when they feel their soul force running low, they would stop refining magic pills and take the appropriate amount of rest before starting again. If not, they could incur some sort of aftereffect. Such as exhausting their soul force and being unable to recover for some time. Or being extremely fatigued, unable to move for a few days, and things like that.