I believe the crop had nothing to do with his illness. Would bet $$ that it was cocci. I would recommend having some sulfadimethoxine on hand to treat acute cases of cocci. Sulmet is VERY hard on chicken's kidney per Dr. Peter Brown.
To prevent acute coccidiosis he recommends treating your whole flock for 2 days once a month with Amprol (Corid). This will keep the colonization of the cocci to a minimum and prevent acute infections.
To prevent acute coccidiosis he recommends treating your whole flock for 2 days once a month with Amprol (Corid). This will keep the colonization of the cocci to a minimum and prevent acute infections.