Please help Simba walk again

Hi my name is Ingrid. I normally wouldn't do something like this but it's an emergency. Four years ago, on Christmas Eve 2017, we welcomed into our home the sweetest, most loving rescued puppy named Simba. He has been such a wonderful addition to our family. This Christmas Eve, exactly 4 years after we adopted him, Simba's back legs suddenly stopped working. We spent our night going from one emergency animal hospital to another. We were told he first needs to have an MRI done to figure out what's going on, and that it will be $5,000. That's just for the MRI, no treatment. He's currently on pain meds and steroids that they sent us home with while we wait for everything to open on Monday. Please help us figure out what's going on with our sweet baby boy. Any amount is so greatly appreciated.