Open Question: Sell personal injury settlement?

I was T-boned coming out of school on 2/5/09. I didnt feel hurt then, but after the x-rays I was told I had 6 torn ligiments in my neck and I believe 4 pinched nerves in my back from hitting my head on the steering wheel. Yes I did complete 3 months of therapy. In March of this year, my lawyer made an offer to the insurance company but they denied because they want more medical records....but now I REALLY desperately need some money so I was thinking maybe I could sell my settlement?? I dont know much about this so if someone could tell me how it all works, what im getting myself into or an alternative, maybe a guess of how much I could get, and maybe who you would recommend? I was thinking JG Wentworth? THANKS!!