The usual conservative (non-surgical) treatment for a mild disk problem is several weeks of crate rest where he's in a crate 24/7 and you carry him out to potty and keep him on a leash, then carry him back to the crate. No running, jumping, stairs, or unnecessary walking. They don't like it, but it's worth the boredom if it helps. The dog may be given prednisone or another anti-inflammatory, and possibly muscle relaxers, a pain med, or other medication. It can take over a month for a disk to heal, so if he was active while he was on the medication recently, he may not have given it a chance to heal. Crate rest is free and may do a world of good.
If the disk problem gets bad enough to cause disability, loss of bowel and bladder control, loss of deep pain sensation, then the best option is immediate surgery, which is expensive and not guaranteed to work, but still the best chance. If you cannot afford it, many people take out a loan through http://www.carecredit.com
to pay for the surgery. If the dog cannot have surgery and remains paralyzed, you can care for him by manually expressing his bladder and getting him a wheelchair and he can still have a happy life. Many people here are caring for paralyzed dogs (I have 2), you can definitely do it if your schedule and ability to lift the dog will allow it.
You can find a lot of information by searching for "IVDD" or "intervertebral disk disease" in dogs.
Here is a website dedicated to caring for dogs with IVDD (especially dachshunds, but also other breeds), giving information on crate rest for an episode such as your dog seems to be experiencing.http://www.dodgerslist.com/literature.htm