It's not a good sign that you got clumps of grass from his crop. He's likely so impacted that this is going to require crop surgery to resolve. No amount of flushes will wash that stuff through his system.
I can walk you through the surgery if you feel up to trying it. At this point, it's likely the only thing that will save this guy.
I can walk you through the surgery if you feel up to trying it. At this point, it's likely the only thing that will save this guy.