It is my understanding that many of the same organisms (viral and bacterial) can cause conjunctivitis as well as an upper respiratory infection. Clavamox covers common skin and mouth/respiratory pathogens in humans, and I have given it to Polly before for sneezing/URI.
Currently, my “kitten” is on tobramycin eyedrops; he was squinting his left eye and the conjunctiva (inside of the lids) was reddened with prominent vessels. Is this what you are seeing? (However, he has not sneezed once and has reddened gums; my husband can’t remember what they’re treating him for, but it is something different from the usual URI.)
How many days has Lacey been on the Clavamox? If she’s just started recently, I would call the vet and mention it/see what they think; I suspect that they might say, wait a few days and bring her back if it gets worse,
.