If its paramyxovirus then neither Baytril, Parastop, nor Amoxicillin will cure this as antibiotics cannot treat a virus, these will only treat any secondary bacterial infection and could make the situation worse If it is paramyxovirus then you need to support the birds with vitamins / electrolytes in the water, ( they will be drinking a lot of water ) and feed them on pellets only which are digested easily and will stop them scattering food everywhere when they are sick which will help reduce spread of virus when other birds eat spewed up corn The loft floor will be wet so the slops need to be scraped up and floor dried of with gas burner then a scattering of staloson F or shavings applied daily If it is paramyxovirus there is no short cut to a cure but you should see some improvement after about 3 weeks, i assume they have not been vaccinated previously against this so in the interim some will probably die and any that display twisted necks etc will not fully recover and should be culled Hopefully after a month or so the virus will have run its course and most of the birds will have survived or recovered when they should then be vaccinated with Nobilis or Colombo-vac where this should be ongoing on an annual basis Some may not agree with the above advice but that is how I would proceed having had some experience with this viral disease on an occasional basis since it first came on the scene in 1983 ( above assuming it is paramyxo ) where it Deffo sounds like it Hope this helps