If your Pigeons are showing signs of illness, do some searching and reading, there is a generous amount of information concerning illnesses the Pigeons suffer.
Recently my Pigeons became ill, I came to the conclusion they were suffering from Salmonellas.
Here are my finding and links to support my findings; I will also offer some house hold items to help.
As always it will be to you the reader to decide if this will work for you, I can not and will not make any promises, I am treating my birds with success, this may not work for you and I am not claiming that it may, I am simply informing the reader what is working for me.

I began seeing my birds were inactive, fluffed up, this told me they were ill, and then I began seeing the birds weaving, un-balanced, and unresponsive.
I began seeing loose, runny stools; this told me I was dealing with some form of intestinal infection and or maybe a virus as many birds were displaying these symptoms.
I began searching for information on what I suspected.
I began with West Nile, as I was seeing many Mosquitoes around my birds, after eliminating this as a cause I moved on to food poisoning, in the mean time 3 birds died.
I became more desperate for answers and reached out to other Pigeon rescue groups and found no help, only criticism and folks pointing out my mistakes.
Here are the sites that helped me locate the problem and treat the problem.
http://www.chevita.com/tauben/e-index3.html
Here is the site where a person was willing to help
http://www.aviary.info/?
I also was advised to offer Apple Cider Vinegar to help concerning this issue.
I was also advised to continue to hydrate all birds.

I am cleaning the loft with bleach daily, sometimes twice, I am using ringer’s solution to keep the birds hydrated, a small amount of salt and sugar added to the water.
I am using Bird Biotic, Doxycycline Hyclate for treatment, and one capsule to a cup of water.
This treatment will continue for 7-10 days with direct syringe into the crop.
After this treatment I will wait a few days before beginning a respiratory plus preventative treatment.
I have thrown away all seed and replaced with new seed, I have bleached & rinsed all feeders.
I continue to clean the loft sometimes 2 times per day.
I have removed all straw.
I sweep up any and all seed thrown around by the birds.
This is what I am doing to help my Pigeons, this may or may not help you, this is for you to decide.
Arty/BrokenWing