Last week, I purchased a pair of golden sebrights to raise for showing.They are both a year old. I checked them over for health issues at the farm and they seemed fine, but a few days ago the rooster started sneezing excessively and has some gunky stuff in his nose. His eyes and comb and wattles are bright, and he is eating and drinking and seems healthy, except for the sneezing. The hen sneezes occasionally, but not often.They are quarantined and far away from the rest of my flock. I know respiratory things are nearly impossible to diagnose, but is there anything I can do to strengthen his immune system? Thanks!