New Dog Not Going to the Bathroom?

I have a 9 year old dog that came from a multiple dog home of a disabled owner. She was newspaper trained and never walked outside. I've had her for 3 weeks and was doing pretty good with potty training, as she would consistently go back to the pad, but would pee right on the edge so half would go on the floor and half on the pad.

I thought I would try litter box training her so I tried to introduce one, but instead she got very anxious and now can't figure out where to potty and instead starting just going on the floor. I tried confining her to the area with the entire floor covered in pads, but she refuses to go. It's been about 18hrs since she's peed or pooped. She ate breakfast as usual and I have spent the last 8 hrs either confining her to the area of the pads or crating her and bringing her back to the pads or just letting her relax with me on the couch and periodically bring her back to the pads and ask her to potty but she won't.

I don't know what to do and am worried she will rupture her bladder if she refuses to go. She will sleep comfortably right next to me, but when I bring her back to the pads she just sits there and looks and me no sniffing, no walking around, and won't go pee or poop. I've tried pads with attractant, newspapers, attractant sprays, and have tried taking her outside she won't go at all. I'm at a loss?