[Pink Dog]

loss of function in back legs?

My sweet baby girl will be 7 y/o in April and has had a healthy life thus far. However, a week ago her back legs started slipping. We have concrete floors which can be slick and she hasn't been groomed in awhile so my husband thought her paws needed clipping (so I did). That still didn't help as the next day she got worse. We took her to the vet and he thinks it's medial subluxating patella and ordered 5 days of NSAIDS since her ligaments are likely inflammed. Through all of this she hasn't exhibited any signs of pain. The concerning thing is that she has gotten worse even though she has had 2 days of medicine. We bought rugs to put down for her to walk on but she still falls and sometimes her back legs feel stiff. She can't walk at all on the concrete floors now and looks like Bambi on the ice when she tries; this is why we put down a few rugs. I'm very afraid that this is more than what the vet thinks. Does anyone have experience with this? Should I keep her from walking altogether or encourage her to move so she isn't stiff? Any advice? TIA!

~Worried!