Shocking news, Trev. My heart goes out to you. So much work and effort gone, just like that. It guts you, I know.
Yes probably PMV, but Buster might have got it too, Rota. That kills them real good.
I note your comment about high protein feed causing digestive upsets. I would put that out of your mind. In years gone, pigeons were raced on beans and peas, and because that was all they knew they did fine on it. Some people still feed the stock pigeons only peas or beans. I think that is wrong, but who am I to say?
What appears to cause digestive upsets is suddenly changing the corn. When I found mine were hungry for carbohydrates, in the cold, and leaving the legumes, I simply reduced the legumes, peas and beans, from 20% to 10 %. The rest of the mix is the same. The birds eat what they need, and I am not throwing peas to the doves.
This morning the birds had two trays of this,
This is what they left
Not much left for the little wild doves, so I threw them a cup of wheat as well.
I hope your problem is sorting it'self out, Trev. Keep an eye on thge ones that recover. They can look okay after Rota, but they can't stand training for a long while, some of them.