I've just reread your original post and the initial symptoms of walking backwards and flipping over are neurological, as is an unsteady gait ..... can you take some video footage of her walking and upload it to You Tube or Vimeo and then post a link. I'm thinking this may be Marek's rather than a laying issue or perhaps both. Serama are one of the breeds that are particularly susceptible to it.
If she was laying internally there is no way for egg yolk material to get into the digestive tract, so I don't agree with the diagnosis of EYP. I think it is more likely to be salpingitis and some yolk got squeezed past the blockage in her oviduct. Antibiotics would help to control that but it is unlikely that she would manage to lay eggs properly ever again and eventually it would lead to internal laying as the oviduct becomes totally impacted. Marek's suppresses the immune system and makes them prone to infections as well as the neurological inflammation and eventual tumour development. If she is continuing to ovulate (ovaries releasing ripe follicles) then this is a ticking time bomb. A hormonal implant might buy you and her some time but the stress both of having it done and the hormonal change might aggravate the Marek's if I am right about that. Having said that, if she continues to ovulate she is almost certainly going to die anyway if those eggs can't come out, so there might be nothing to lose in giving it a go .... apart from a chunk of cash! Xrays might give you a better idea of what is going on but I believe they are very expensive and may not be conclusive.
I have Marek's in my flock and I know how attached you get to the "special" ones that you invest time in nursing for weeks and months. It is hard to know when to keep going and when to let them go and the longer it goes on, the more attached you get and the harder it becomes. My rule of thumb is, if they are bright eyed and interested in food, then I give them every opportunity to fight it, once they lose interest in food, then I end it for them.
I wish you luck with her. She is a sweetie. If you decide to go for an implant (not even totally sure they can insert them into such a small bird) let us know how she gets on please. It would also be helpful if you can let us know how much it cost as these things should come down in price as more people opt for the procedure and vets become more experienced at administering it. The price can vary quite a bit between establishments too, but I'm thinking you are going to need to find an avian vet to treat such a small chicken, so less opportunity for shopping around.
If she was laying internally there is no way for egg yolk material to get into the digestive tract, so I don't agree with the diagnosis of EYP. I think it is more likely to be salpingitis and some yolk got squeezed past the blockage in her oviduct. Antibiotics would help to control that but it is unlikely that she would manage to lay eggs properly ever again and eventually it would lead to internal laying as the oviduct becomes totally impacted. Marek's suppresses the immune system and makes them prone to infections as well as the neurological inflammation and eventual tumour development. If she is continuing to ovulate (ovaries releasing ripe follicles) then this is a ticking time bomb. A hormonal implant might buy you and her some time but the stress both of having it done and the hormonal change might aggravate the Marek's if I am right about that. Having said that, if she continues to ovulate she is almost certainly going to die anyway if those eggs can't come out, so there might be nothing to lose in giving it a go .... apart from a chunk of cash! Xrays might give you a better idea of what is going on but I believe they are very expensive and may not be conclusive.
I have Marek's in my flock and I know how attached you get to the "special" ones that you invest time in nursing for weeks and months. It is hard to know when to keep going and when to let them go and the longer it goes on, the more attached you get and the harder it becomes. My rule of thumb is, if they are bright eyed and interested in food, then I give them every opportunity to fight it, once they lose interest in food, then I end it for them.
I wish you luck with her. She is a sweetie. If you decide to go for an implant (not even totally sure they can insert them into such a small bird) let us know how she gets on please. It would also be helpful if you can let us know how much it cost as these things should come down in price as more people opt for the procedure and vets become more experienced at administering it. The price can vary quite a bit between establishments too, but I'm thinking you are going to need to find an avian vet to treat such a small chicken, so less opportunity for shopping around.