Why does my 5 year old female Shiba Inu "go" in the house even right after she "goes" outside?

Foxy , my Shiba Inu dog will be 5 July 11th. I bought her for my birthday when she was 2 months old so this is NOT a life long behavior... Over the last few months, Foxy has decided it's cool to pee and poop on our floor either at night or when we are gone... Even if I step out int to the laundry room (directly outside of our unit) for just a few minutes. Here is the ironic part... She is in perfect health, smart, pretty... SMART. So even after we take her out to do her business outside, if we leave her for any amount of time short or long, she STILL manages to let it out on out floor. Even if it's a few dribbles of pee or a pellet of poop! It's almost like she has to SQUEEZE it out because she is mad at us. Could this be separation anxiety? Or is it just Foxy being a jerk?! We are at out wits end and contemplating giving her up. I don't WANT to, but I don't want my kids rolling around on soiled carpet. She is AMAZING with my kids... Perfect "kid" dog. Takes their terrorizing like it's nothing. So she is very sweet. But I just don't know what to do. We've got limited space so a "crate" isn't going to happen. Especially without a bark collar since Shiba's scream. HELP!