If you are up to it, and it's no shame if you aren't, you could perform a do-it-youself necropsy and look inside her to see what might have killed her. Two things might be obvious to an untrained person. One would be a soup of small pea-size tumors floating in her abdominal cavity. This would indicate EYP or internal laying. There may be full size eggs floating there that appear to be cooked.
	
		
			
		
		
	
				
			
	
I'm so sorry to hear about Jessie 
  Who knows.  This thread is from last year, I believe the hen didn't make it.