I have tried olive leaf in their water, which is an antiviral and antibiotic and some vitamis I got at TSC, most of them are over it - but the Marans head never recovered. I think MG stands for mycoplasma something or other. I am going to try the Tylan 50 antibiotics next, but really I am...
I have a cuckoo marans with the exact same symptoms - actually her neck is a little worse, and sometimes she walks around in circles - a lot of the time she holds it completely upside down - I would cull her, but otherwise she is happy and eats and drinks with no help from me.
All my chickens...