Went to lock up my chickens in their coop tonight and noticed one of my 4 1/2 month old Silkies was sneezing and a little clear moisture coming out of one nostril. I came in and did some reading on BYC, gathered up my courage and set out to give the little chicken some Tylan50 (which I bought along with some terramycin and syringes last week). When I got out there I noticed my other black Silkie (they hang out together) was also sneezing. Nostrils don't look swollen, poop looks normal, eating fine, eyes are still clear and they don't act sick. They did seem to be trying to swallow more than usual though and scratching at their nose/face. I gave them both 1/4 cc injections. Is there anything else I should do? Anything in the water, vitamins, ACV? Is 3 days the normal dosing time? These are my first sick chickens. I will be watching others closely. I have a feeling they got sick after being out in the rain last Friday. Most of the other chickens had sense enough to go into the coop, not my Silkies. Is it likely the rest of my flock will get sick too? Thanks in advance for any advice!