Hi there and thank you for your question. I am a licensed veterinarian and would be happy to assist you. I worked in emergency and critical care medicine for 6 years and worked with a neurologist. If you are not ready to put him down and want to try anything you possibly can, if I were you, I would try admitting him to the hospital for high doses of IV steroids for 2 days and see if things get better. I would also take him somewhere that has access to a therapeutic laser, because laser treatments can help, and they are affordable (~$45 per treatment). If neither of those treatment options are affordable for you, then I would take him home and try oral steroids and cage rest. In 5% of cases or more, simple cage rest over 4-6 weeks can allow a dog to regain the use of his hindlimbs and bladder, even if it is just a little bit. Pain, in the short term, can be managed with oral pain medications. If he is not better in a month or so, you can consider a wheelchair for him if he has bladder control by then. If he has no bladder control at that time, I would consider putting him down. Here is a link to a wheelchair site:
Hope this helps. Best of luck.