Oh you poor thing.
it makes me cringe when i hear professionals say things like that. After a right roller coaster ride myself, I learnt that most discs eventually "go" when you sneeze or soemthing lame (because you don't guard like when you lift a TV) but it isn't the sneeze or getting up from the rail that actually "did" it, but the years of degneration prior to the elastic band snapping. A really good web site ishttp://www.chirogeek.com/
explains the back really well.
Leaning forward as instinct relief is another classic sign that in my case was over looked. Also, be careful with the SLR (When they lift your leg at 90 degrees to see if you have back/leg pain) because of HMS I could all of it, somersaults too (i jest) but this gave a wrong assessment to the health professionals - I think they thought i was lying!
It is very worrying when text book symptoms are ignored. Perhaps you should try a different Physio? The boards here say how important it is to have one that fully understand HMS and I have to agree with that too.
There is also a school of thought that thinks that once the disc has been damaged, the fluid becomes "toxic" to the body and causes pain.
Take care and no heavy lifting!
xMod edit - link fixed