Hello, my name isXXXXX and I have over 20 years of experience as a veterinarian.
I am sorry to hear that Sparky has had a disc disease flare up.
Ideally he would see his veterinarian because your veterinarian can prescribe a steroid or nonsteroidal anti-inflammatory to relieve pressure on his spinal cord and nerve roots, as well as something for pain too, such as Tramadol. And if he is having painful muscle spasms then a muscle relaxant such as methocarbamol as well.
If that cannot happen for whatever reason please do not give acetaminophen or ibuprofen. These aren't used in dogs because their effective doses are very close to a toxic dose in dogs.
The only over the counter anti-inflammatory that can be used in dogs is buffered, enteric coated aspirin (like ascriptin). Aspirin does cause stomach and intestinal irritation and ulceration as well as clotting problems so should not be given for more than 2 to 3 days consecutively and should always be given with a meal. If you choose to use it watch for lack of appetite, vomiting, blood in the stools or dark tarry stools and stop immediately if you see those. Do not use aspirin if your dog has liver or kidney disease or a history of a sensitive stomach or clotting problems.
The dose for aspirin is 5mg per pound orally every 12 hours (about one half of a 325mg a 25 to 30 pound dog every 12 hours). Always give with a meal. Do not use for more than 2 or 3 days.
Be aware if you choose to use aspirin and it doesn't help your veterinarian will be limited on what they can give as there must be a 5 to 7 day washout period between different nonsteroidals or nonsteroidals and steroids.
He should be closely confined starting now. No stairs, running or jumping. If you have a crate for him I highly recommend using it. The less he moves around the more comfortable he will be and the faster he will heal.
He should go out on a leash to relieve himself. Do not use a collar for him, a harness which more evenly distributes forces if he pulls on his leash is better.
You will need to confine him for several weeks, even as he starts to feel better or he may reinjure himself.
Keeping him on the thin side is recommended to decrease stress on his back, but
is no guarantee that he won't have another episode. Once a dog has one bad disc
the likelihood of another is very high.
You can try alternating warm and cold packs on his painful areas for 10 minutes at a time several times a day.
Long term for joint and back pain I do recommend using a combination of a
glucosamine/chondroitin product (examples are Dasuquin or Cosequin) and an omega 3 fatty acid (like 3V Caps or Derm Caps). These work synergistically and
improve cartilage health and joint fluid quality and quantity as well as reducing inflammation. They can take several weeks to see full improvement but some dogs do very well with them alone. They are available over the counter.
Another option is a product called Duralactin. This is an anti-inflammatory product derived from milk proteins and it also has omega 3 fatty acids incorporated into it which can be very helpful. See this link for further information: http://www.duralactin.com/products_canine.htm
If you are interested in reading more here is a link to an excellent article about intervertebral disc disease, its causes and therapy: http://www.petwave.com/Dogs/Dog-Health-Center/Bone-Joint-Muscle-Disorders/Intervertebral-Disk-Disease/Symptoms.aspx
Best of luck with your fellow, please let me know if you have any further questions.