Help please back injury advice needed asap

[Lamborghini23]

Hi i am a serving soldier in the artillery i have served just over 4 years and recieved an injury in febuary 2012 during a pnco cadre course at first i was just given pain killers i was then given physio and they believed i just had tightened muscles in the lower back, when physio was not working and my pain was getting worse i awaited an Mri scan results showed The following;

There is straightening of the lumber lordosis present theirs a grade 1 retrolisthesis of L5 on S1
Theirs a diffuse reduction in the marrow signal seen on both the T1 and T2W images consistent with persistent red marrow. The conus appears normal and terminates at T12/L1. At L3/4 and L4/5 their is a posterior central/left paracentral disk herination present indenting the thecal sac anteriorily and contacting the left S1 nerve root as it exits the thecal sac.

I am now on tramadol and amitriptyline with my condition not improving i have been referred to an orthopedic doctor who will give me a steroid injection 11/03/13... I have been really down lately as i am temp downgraded restricted of pretty much everything and fear i may not be able to carry on in the army and i will never have a normal back even after surgery if it comes to it. I am currently claiming against the mod for this injury.

I was just wondering if anyone could give me any advice on the process of medical discharge would i be considered for this?
If so what is the process how long am i going to be waiting in pain not knowing whats going on or what happens next?
Is my injury classed as 20% + disability which would make me elegible for medical discharge?
What are my options!
Please help no one can seem to give me answers.. This will effect my life and it is really worrying any advice would be much appreciated! Thanks.