It may be Egg Yolk Peritonitis unfortunately. I just lost one of my oldest hens to this about 2 weeks ago. She's not laying an egg because she's laying them internally with no shells. The eggs build up in the body cavity to the point it distends the abdomen area from the pressure build up. I was able to keep my hen going for almost three months but it was like a rollercoaster with weeks of being back to normal due to expelling some of the material and her body absorbing some, followed by a week and a half of not eating, not drinking, not walking anymore and me having to tube feed her to provide comfort until one of two outcomes occur. She either will pass away from too much buildup, infection, or she recoops enough for another month. Unfortunately the only cure is to prevent further egg ovulation. Apparently it's hard to find a Vet willing, in addition very costly. Good luck and my prayers are with you and your hen.
