That does sound like a back problem. Have you ever had sciatica? That pretty much describes it. Shooting excruciating pain down your leg from your butt or lower back.
I am not sure what you mean by the word "attack". If you mean an MS flare or exacerbation, well those are pretty hard to describe because those are different depending on which part of the brain or spinal cord is being damaged by demyelination. My first "attack" caused severe vertigo with nausea. I ended up in the hospital for a couple of days because I could not walk with the spinning (lesion on the cerebellum). My most recent "attack" caused numbness and some nerve pain from the waist down (spinal lesion). So it is really hard to say.
It sounds like your doctor put you on a pain reliever with a steroid. That may be why you felt so good. That would have relieved that pain and gotten the inflammation down so the pain didn't return. Steroids usually give you some decent energy. I am not sure what a dose pack is (sorry ).
MS flares last longer than 24 hours so you can rest assured that that is not what it was. The definition of an MS flare is any residual symptom that is significantly worse or new symptom that lasts longer than 24 hours. My last flare lasted several weeks.
Keep asking questions. That is why we are here.
Gretchen co-moderator MS board diagnosed with MS July 2006