Repeat Case: Hen with Swollen Bottom

The very first time this happened was with my hen, Puffy. Her bottom got swollen and I thought that she might've just been constipated or maybe just had a very big egg she needed to lay. So, I gave her some olive oil in case she was constipated and that didn't help. So, after that lasted for a month or so, I started giving her antibiotics to see if she had an infection in there. That didn't help either. Eventually, after multiple months, she quit eating and drinking- we eventually had to put her down.

Now, the same thing is happening with my hen, Phoenix. This time, I wondered if there might be an egg buildup in there so I got some surgeon gloves and tried to feel if there were any eggs. I don't know if I did that quite right but I didn't feel any more than 1 egg in there. So, I have no clue on what to do. Any help given will be greatly appreciated!