I had a disc problem for years now, almost 3 years. I had a discectomy last year (june '13) due to my left sciatic nerve pretty much stopping me using my leg. Pain, numbness, pins and needles, the pain pretty unbearable, but even within that, I got periods where it was entirely bearable, and I would think 'oh yey! on the mend!' than a further lapse, new MRI to show it was worse. But, I am a minority.
My surgery was, really, very successful, in that it untapped the nerve, and I woke with significantly less pain in my leg than I went to sleep with when I had surgery. I recovered really well, little difficulties, some steps forward and back until about 11 weeks onwards and I then started to get leg pain again, then back pain, then Boom, worse.
The disc has re-prolapsed, but not significantly, so it seems, although I have endplate damage (the part of the vertebrae that touches the disc), and the disc is sick/dying too, so much of the pain is probably from that.
However, worth mentioning that I also have a very slight vertebral misalignment (retrolesthesis) which may/probably did contribute to my prolapse and possibly to this second one.
Fusion is the only next step for me really, but my surgeon is not proceeding, doesn't want to to do it. So off to London for me on 16th October to meet with a specialist for a second opinion on that. As, no fusion, no improvement for me long term.
RE; Injections. Now, I had one almost 3 years ago, at the beginning of my problem. I got about 2-3 weeks from this. Nothing spectacular. But, just had it done again in August, after much fighting as docs said it won't work, and it was marvellous. It lasted about 5 weeks? With some deterioration within that, but not sudden, til near the end then it sped up leaving my system. But. 5 weeks is better than a poke in the eye!
Unfortunately, I am largely back to where I was about 3 years ago in terms of pain levels. And I can't take gabapentin, pregabalin or amitriptyline, as the side effects are far too strong for me. Shame as they are fab, amitriptyline in particular almost completely got rid of my nerve pain, over about 2 months though.
Take the gabapentin at night. It will make you drowsy. Take it, I would suggest, around 6-7pm to reduce any 'hangover' the next day. And give it at least two weeks for the side effects to wear off.