My ragdoll kittens are sneezing and goopy eyed after antibiotics stopped?

i am worried that my cats may have fiv or feline leukemia because they keep getting URIs. they just finished with their clavamox which was given because they both were sneezing and the older one had green goop in his eye. now, as soon as they are off antibiotics the little one is sneezing like crazy and has green goop in both of their eyes.....what is going on? they are both still very active and are eating and using the litter box....i am very worried about my kittens