No eggs since spring, now she's laying, but acting weak

I asked what might be wrong with Kiwi in another post, but now I'm thinking in a different direction, so am starting a new post.
Kiwi is a 7 and 1/2 year old easter egger. She's been fine, but I found her laying under the roost this morning, unable to walk. She seemed healthy and normal in every other way.
No swollen abdomen, healthy vent, etc.
Here's my question: My chickens are getting sort of old, so if they don't lay eggs, I don't think anything of it. I got a few in early spring, and then it stopped.
But.....someone has been laying a couple eggs recently, but I didn't know who.
After finding Kiwi on the floor, I put her in a dog crate with food and water and started her on antibiotics. I went to check on her this afternoon, and she had laid an egg. She's a little perkier, but still wobbly and laying down most of the time.
Is it possible that she's been laying internally all summer and just now able to get a couple out?? Wouldn't her abdomen be swollen?
Would 1 stuck egg cause her to not be able to walk?
I was thinking that maybe she hit her head on the roost and had a concussion. But now I'm wondering if she's been laying eggs inside her, and they've been getting absorbed okay. If this is the case, is it weird to then start laying again, in Autumn? I don't extend the daylight with light.
Any ideas?
Thanks.