Hey thanks for the reply I appreicate it, You're right I'm not a physio. I got the phsyio on the nhs. I asked him what he thought could have initially happened to me and he said it could of been a number of things (which I cant remember).
I asked what happened exactly and he said not to worry about it and gave me the loss of motion explanation. I really wanted a title to my problem so I know what it was.
Im desperate to fix this problem.

I have been doing all the exercises as instructed.

First the physio asked a serious of questions of how it happened, when does it hurt, could you rate the pain on a 1 to 10 scale.
He then told me to take off my top asked where it hurt from and made me so some stretches like touch your toes, hamstring stretch, side bends and putting both legs to my chest. I did all this and then made me lie on my front and really pushed hard on parts of my spine and said that L4 and L5 didn't go down as much as the others.
As I told him that I had trouble bending over and had avoiding doing this rather squatting down, he said I should be bending down more as the more I do this the better my range of motion would become.

I asked if it was serious and he said no.. but Im not convinced to be honest.
I am really seriously considering going to see someone, I live in Coventry could someone recommend whether I need to see a physio or chiropractor? I really don't know the difference