My dog Buster was boarded at our usual kennel for four days.When we picked him up and he arrived home, he could not jump up into bed or onto chair. We brought him to the vet (kennel and vet in same place) who said he had herniated disc in back. They gave him steroid shot and pills. Buster is very shy and skittish 7 yr old terrier mix. He has been back to dr. 3 times for not eating or drinking and in extreme pain. He will not eat or drink (second day) and refuses medicine. We fight him to get liquid steroid into him.. he gets so upset it seems to make his back worse. He is also on morphine patch.
Can a dog deteriorate so rapidly without any known cause for bad back. How long can he go without food or water? When does one know how much suffering is too much? My heart is breaking as I do not know how to help him. Money is an issue.

Here is a little information on disk disease.

http://www.marvistavet.com/html/body_intervertebral_disk_disease.html

Standard treatment is pain relief, steroids and cage rest.
Treatment may also take a while, weeks even.
7 is not that old, try not to let this turn your thought negative.
Very frustrating to not be able to get the pain meds in.
Is he on an oral pain medication or just the morphine patch. (Fentanyl?)
If memory serves me the patch is effective for about 3 days.
Fighting with him to get the meds in is not in his favor, I do get that he is giving you little choice though.
Is there another way? A favorite treat, cheese, peanut butter, yogurt?
Pill pockets or even a small piece of lunch meat?
Basically, whatever it takes
Being painful will frequently take them off their food.

Did the vet take an X ray?