I apologize that no one has responded to your question sooner. Different experts come online at various times. I just came online and saw your question. I'm sorry to hear that your little Milly is having this awful problem. I have been raising and showing rabbits for over 30 years, and have had numerous experiences with wry neck. I'll try to answer your questions.1. would penicyllion be a better antibiotic?
No, it wouldn't. Rabbits are very sensitive to antibiotics, and some including this one often result in death when given orally. Here are two sites with good information on rabbits and antibiotics:
http://www.medirabbit.com/Unsafe_medication/dangerous_antibiotics.hm2. do I continue with the metacam for pain?
It will more than likely be all right to do so, but the condition may not even be painful. It is neurological in nature, and while the twisted neck looks painful, it is probably disorienting and stressful, but not actually painful.3.and should I try to brace her neck?
No, the problem most likely is the result of something interfering with the brain's communication. Bracing the neck will only distress your rabbit a great deal.4.have you had experience in this before?
Yes, my vet and I use Barbi Brown's protocol, and have found it effective about 90% of the time. Panacur is another effective treatment. E. cuniculi is the most common cause of vestibular disease (wry neck), but there are other possibilities.It can originate in either the ear or the brain stem. There are many things that can go wrong in these structures that will cause the symptoms you are seeing. There are protozoal infections, bacterial infections, a disease spread by raccoons, strokes, and injuries, to name a few. When it doesn't respond to antibiotics and either Ivomec or Panacur, you will need an experienced rabbit vet to figure out exactly what is going on and begin an appropriate treatment. Here is a link to a directory of Australian rabbit vets:http://members.shaw.ca/cocoasun/AustralianRabbitVets.htm
If none of them are close by, see if your local vet would work by phone consultation with one of them to treat your rabbit. I hope you'll be able to find a solution for your rabbit. Let me know if you need anything else.