Due to this I'm sure but it's all still speculation/assumption ofc. It seems most likely to be happening though imo. Zoro can't move too so it would explain it. Unless he's that badly injured from fighting King too and can't move anyway so he's completely vulnerable to face the vicious assault of pain from the medicine wearing off and he can't go somewhere safe and get help or something before it does now.
In other words, he's "paralysed" right now and whether the medicine has worn off now or not, he's completely helpless. If it hasn't worn off yet, then he might black out at least but that grim reaper might have appeared because the pain might kill him this time when it kicks in if it hasn't already ofc.
Zoro almost died from the Nothing Happened moment right? It felt like he was meant to die then and seems like Oda is deliberately throwing back to that and trying to make Zoro even closer to death now, really dancing with it with the almost literal at least incarnation of Death right in front of him.
In other words, he's "paralysed" right now and whether the medicine has worn off now or not, he's completely helpless. If it hasn't worn off yet, then he might black out at least but that grim reaper might have appeared because the pain might kill him this time when it kicks in if it hasn't already ofc.
Zoro almost died from the Nothing Happened moment right? It felt like he was meant to die then and seems like Oda is deliberately throwing back to that and trying to make Zoro even closer to death now, really dancing with it with the almost literal at least incarnation of Death right in front of him.
Chopper was just hinting at it.