Oh dear D what a tale of woe. Maybe you need to step back a bit and go to a simple regime of treatment and nutrition. First of all I don't know what the RM spray is but if it's Barrier it's not effective and doubly so if sprayed on the house and not the chx, if it's Mite Kill it'll be very expensive and not very effective either. You maybe overdoing the RM spray so I'd stop that immediately and tackle the RM with FicamW and Diatom. Invermectin isn't very effctive at getting rid of a RM infestation as they only visit the birds in their later nymph life stages and as adult mites. It will kill them but won't do it in short order. A residual pesticde like Ficam will and have a lasting effect. Diatom slurry painted on the perches after the initial infestation is gone is an effective preventative. Don't dust it as you obviously have a respiratory infection issue too and dust is the worst thing you can do in the house where it will iritate their breathing and sinuses eyes etc and be a dangerous infection vector for viruses. By all means use Poultry Shield but cheap washing up liquid with a dash of Vanodine V18? disinfectant is equally good, if not better, and a lot cheaper. Use this to wash out (all detergents will disinfect many bacteria and viruses).
Anti biotics. How long did you treat them with Baytril as it sounds as if you may have stopped too soon. I like to use for a min of 5 days and 7 is the norm. Usually 3 days is showing a big improvement but you still need to complete the course. Tylan maybe an alternative a/b to try assuming the Baytril isn't being effective. Do they rattle (ie a gurgling breathing) if so a lower respiratory infection maybe the problem. These are difficult to shift and may well never be solved and your birds will continue to be carriers. The eye bubbles and nasal discharge and sneezing is a sign of a seccondary upper respiratory infection against which a/bs are usually effective. However I agree with Orchardlady thet your birds seem run down and stressed so will be susceptible to further infection. Good nutrition is essential in building them up but personally I'd not use tonics and pick me up supplements but keep nutrition very simple layers pellets in the day only and treats and mixed corn and the tuna might help in the evening. If they are free ranging I would think that the greens aren't needed and I rather not bulk them up with high energy foods during the day. The only supplement I've consider would be a multivit and there are other cheaper and as effective ones available as Lifeguard, which has all the hallmarks of a quack tcure all reatment. Try the one in the photo available from Wells on the web or any good farmers store. Much cheaper and lasts well.
In short try to avoid stressing your birds further without chopping and changing their feed regime, treatments and over handling. Get to grips with the RM using an effective pesticide and cleaning regime, cut out the over the counter patented sprays and magic cures and on bird treatments. Keep them dry sheltered and as quiet and warm as possible with the basic simple nutritional diet.
HF
