your best bet is NE pigeon supply, it'll make it in a few days.. if you wait too long it will be a mute point.. Yes its expensive, but if it works you save some pigeons, they will be carriers of it , that is what i have heard. but its better than waiting for them all to die or try to save a few.. Kinda your call..
You might consider getting them vaccinated for PMV.. and keep 4-1 around or some basic meds to treat with, i always have a coxy treatment on hand, wormer, vitamins, probiotics,, and a canker treatment, and salmonella as well. better to have these meds on hand for just this type of t hing...., dont need to wait a week in the future, next it might help to take a dead one in for an autopsy, or diagnosis to find out what did go wrong,... and if you dont normally do it , get a vac kit from NE Supply as well.. certainly can not hurt..