Paul, I am no expert but I have found that with backs its best to get it checked out rather that carry on.
Maybe just a trip to your GP would be advisable and take all there advice and information into account.
You know your self when an injury is just a niggle but as you've posted on here to express your concerns that tells me that you have more than just a slight concern about a niggle that will pass over in a few days...get it checked out, after all GP's are free
I have been advised by a sports physio to attend a Chiropody & Bio-mechanics clinic to have custom made orthotics for my running trainers, as I am suffering from calf/'shin pains apparently down to my running style.
I have been advised that the orthotics would cost me in the region of £200 and last approx five years.
Does this sound rather expensive? could anyone advise a good person to go and see in the Leeds/Bradford area?