Young BR hasn't laid in nearly a month

I have a Bantam BR 10 months old who normally lays a perfect egg almost daily. She eats flockraiser with free choice oyster shell. She acts fine, but she stopped laying almost a month ago. I feel something small, roundish and kind of firm, but not hard like an egg, in her. About the size of a ping pong ball. I can move it around a bit but it stays in the same place. It's not between the legs, and not close to the vent, but between these areas.

So I took her to the vet 2 weeks ago. X-rays showed no eggs and he felt her and said what I was feeling was her intestines, but I'm not so sure. He is a highly regarded vet, but is used to seeing parakeets, parrots, etc. He seemed surprised that she lays nearly every day. He couldn't find a reason for her not laying, and said she was probably just taking a break. He is the only vet around that sees chickens, but I don't think he understands a chicken's laying habits.

It seems odd to me that a young BR would stop laying for this long for no apparent reason. She's not broody, and not molting. It's been hot here, but the other hens are all still laying. At this point, I don't know what to do next. I can still feel that 'something' in her. But if it was a tumor or infection, I think it would've shown up on the x-ray? Or maybe it really is her intestines?

I had posted previously about this hen on the 'emergencies' board and got one reply that said I was feeling her gizzard. I'll be so relieved if that's right, but it seems too far back to be the gizzard, I thought the gizzard was further up, more between the legs (but I'm not sure about that). Even so, that still wouldn't explain why she's not laying. What should I do here? I figure my only choice is to take a 'wait and see' approach since she still acts perfectly normal, but I would like to hear your thoughts.

 

Thanks for the reply. Yes, I have checked the other hens for comparison, but they don't have exactly what I'm feeling in my BR. I can feel something in them, but it's much smaller and higher inside their bodies. I assumed it's their gizzard? But they don't feel quite the same as my BR.

She's at her prime laying age, and I have no idea why she would just stop laying for this long. The x-rays didn't show anything was wrong, but I'm getting pretty worried, even though she still acts okay. I'm not worried about getting eggs, I just want her to be okay.

edited to add: I read on another post that some hens will take a break from laying to rejuvinate their shell gland. I've never heard of that, does anyone know more about it?