J. M. H. O. . If all the pigeons are on the loft floor and can't make it up to a perch. I would think paramyxo. And would only add to the water gem ultra-vits because of the excessive water intake of the birds . And all you can do is let it run it's course. But if some of the birds can roost to a perch and its omo. I would treat for paratyphoid and give them nifuramycin. Again always hard when you haven't seen the birds .