Good luck. I will recommend that you avoid (for bio secure measures) that you wear different clothing off your property and on. (I've been reading up on stuff and it's scary) Also, keep in mind that even tho your grain appears clean and dry, it may not have been just prior to grinding the corn, its hard to look at the food issue when it feels like you need to defend yourself from looking dumb. I've felt that same way before too.
ILT is a terrible disease and it is marked by blood spatters at the height of the birds heads. Usually its from them shaking their heads to rid their mouths of blood.
Like I said, there is so many freaky things out there, sometimes I swear ignorance is bliss! Perty chickens. Now I don't put much past the illness' of the birds we have.
Still, if your other birds have not come up with any signs, I'd assume it was what I earlier believed.
Hope you find peace soon, if your bleeding bird is not dead, I would suggest you cull it. Good luck!