Interesting slowmo. You don't do small problems do you, you tend to, as the fast food industry says, go large when you have a problem
A quick Google of the Alexander technique suggests it has merit, posture, is I think, at the root of my problem.
After starting this thread, suffering with pain/discomfort from early July, I'm sitting here this morning feeling a slight fraud. CC threads are often helpful but this may be the first time one has cured someone. I am this morning, largely pain free and comfortable. OK maybe it wasn't the thread but as I suggested further up I thought this was muscular but the stretching I was doing, whilst helping, was not reaching deep enough and I was beginning to feel a bit down about the whole thing. Soldiering on only works for so long.
So what did I do. Well I felt that I needed to use my upper body more, running made my back worse as did impact sports like badminton and squash and hill walking (all of which I've done recently, it being summer and the kids being off, no escape from family activities). Cycling was tolerable and swimming I discovered, very helpful but I'm no swimmer. So the clues were there for me even though I'd reached the point were I was unconvinced I could get on top of this myself without help.
So yesterday I went to the local bouldering wall. Normally I just drop the kids and read, my climbing days very much behind me. This time I didn't, I climbed, carefully, no jumping off though. So with the kids telling me to raise my right foot and just get my left hand down by my left foot and push up, I was very much stretching my body. The fact that they look elegant when doing it and I look like I've been licked and stuck on the wall and am now peeling off is neither here nor there and I digress..
When I finished I thought I'd made a mistake. My back ached. In fact I got out of bed to stretch later on and I went to sleep apprehensive of this mornings pain and determined to re-visit this thread, make a decision and make an appt. So imagine my complete surprise on waking this morning and finding, no pain and free movement. No lurching off the couch in a kind of choreographed mime move.
So now I'm not sure if I need to see anyone. Instead I might continue the stretching, climb carefully and try to become a swimmer and see where that takes me. In the meantime I can see my doc and get a referral as I feel I can wait now and I think a physio will help more by suggesting appropriate exercises based on what I can tell them helps and what doesn't.
I' m also going to change my desk chair, maybe to one of those kneeling ones, feedback on them most helpful before I spend money. I probably also need to think about how I stand and how I sit but most of all I think I need to keep doing something which keeps my upper body supple.
Sorry for the long post and thanks for everyone's input, keep it coming please.