Okay, sulmet seems to be doing nothing, so discontinue. The splits sounds like mareks; stargazing can occur with mareks. There s a possibility that what is going on with these two is unrelated to each other. OF course with as many deaths as you have had, it doesn't seem all that likely, but is still could be.
Have you tried a flush? If not, try it; it will help remove toxins. I would say use molassas as they probably need energy, which the molassas will provide. If you can get a vet to prescribe baytril, that is your best course. Otherwise get either gallimycin (erythromycin) or tylan. Use the strong end of the spectrum in determining the dose. A prescription for metacam might help with neurologic symptoms; metacam is an NSAID. Alternatively, use aspirin water, or if you can get it (prescription needed) prednisone or celebrex.
Are there any vets nearby who will see chickens? THat is really your best bet/