Managed a good 10.5 miles last night at just above marathon pace, back held up well. I really concentrated on form getting my hips forward working my glutes, keeping my back straight and shoulders loose. Had to really concentrate to keep this form towards the end as I got tired, I could feel myself starting to hunch and lean from the hips.
Did a 3 mile treadmill run tonight to "loosen" the back, pleased to say I think it may have worked, feel the best I've felt in a few days, things might be looking up. Will try some light stretching and strengthening tomorrow.