Thank you for your question. My name is***** have been a small animal veterinarian for 14 years and I would like to help with your question.
Neurologic problem such as loss of limb function can be very difficult for general practice veterinarians because it really requires advance imaging with MRI and spinal taps to know what is going on. These are resources that most veterinarians don't have. However, these resources are available at university or specialty clinics and if your friend can afford it, I would absolutely take him there as soon as possible. I wouldn't wait 2 days. There are problems... .such as a ruptured disk that can be treated surgically. And with most of these problems the sooner you treat it the higher likelihood of success.
The thing that you have to know is that neurologic workups to find the problem run in the $3000 range... .and if they need surgery it is even more expensive. But this is an option and if your friend can persue it I would call a local veterinarian and ask where they refer patients for specialty care.
I hope that helps, but if you have more questions please let me know. If not, please don't forget to rate my answer.