Help- internal laying?

Hello,
Hope someone can help.... my 2 year old red hen is ill. I think she has become an internal layer. She's not looked too great the last few days, just a bit down in the dumps. THis morning she's been sitting on her bottom, comb is purple and she's looking really sorry for herself. She's still eating though. I've had a look at her, she has a hard swollen tummy. I've tried olive oil around her bottom and holding her over warm water which has worked for me before when other hens have been egg bound. But it didn't do anything for her, no eggs came out and none of the egg bound ones had this swollen tummy.

I'm thinking she's an internal layer and I'm going to have to cull her. But would be very grateful if anyone could advise on this- either to confirm my diagnosis / advise if anything can be done or if it might be something else......

Any thoughts gratefully received