chicken may have a blocked stomach?

[BCbirder]

I have a hen that had a terrible scabby smelly vent. She eventually lost weight and died. I had given her lots of baths to help heal her skin and I wondered if it was some kind of cancer. After she died I opened her up and her inards looked great except that she had 6 smooth plum pits in her stomach. It is April and there is a plum tree in their pen so I am guessing that they were in her stomach since last year. THese are small plums like a cherry.
Now I am noticing another hen who is acting the same. They make a certain "book book book" sound when they poop as if they are straining and their vent gets poopy.

Is there anything i can do? Would feeding her oil help?
These were both older birds , at least 7 or 8 but otherwise really healthy.
I have lived here for over 9 years and the chickens have always eaten the plums. Last year was a particularly good year for plums.

 

[Judy]

I think oil is what I would try. I don't know whether it will help or not. I also wonder whether this was her cause of death.