When this happened to my piggy, the vet was specialised in small animals and this is what she did. She checked the legs for fractures and in the stomach she found a lump. It was nothing too nasty, it was a hernia that came out due to a rip in the muscle wall which was probably caused from injury to the spine which was what caused her legs to stop working. She examined her back foot and I think she gently stuck her nail between the toes to which my Guinea pig responded showing that she could still feel her foot although it was cold. Meta am and meloxidyl can cause diarrhoea so if this happens, stop veggies and make sure she is hydrated, syringe feeding water if necessary. As long as she has no fractures, gently massaging the leg should help her recover and try not to let her drag it as this will only cause more damage. Maybe try gently pushing your nail between her toes to see if she flinches or tries to pull away. This will see if she has any feeling in her foot. Btw this will not hurt them if you do it gently. Crossing my fingers for you and Ellie