Cefaclor isn't normally used for gonorrhea; in the rare case a doctor prescribed it for that disease, it would be only in a single dose and certainly not with several refills. I can't begin to speculate why she might be taking it, but it certainly isn't an STD.
But why are you asking me? Ask her!
HHH, MD
To add a bit of relief it reminds me or a Seinfield episode where Elaine finds a cream in the guys medicine cabinet and freaks. Turns out it was for his cat.
Why don't you just ask her, you already been intimate. Going through people's medicine cabinet is not cool at all. I am not lecturing, but remind me to never invite you to my house.