A visit to the GP should be done with the aim of getting a referral to an NHS physio.
I've had a similar injury to the one you describe (OK I displayed the same symptoms, that might not be the same thing). But I had mine as a result of fairly intense Karate training. I carried it around for about 6 months, trying to work around it but it just didn't get better.
I am not normally one for recommending cuckoo science, but I did in the end have accupunture on it and following that, the injury cleared up. I'd like to think there was something scientific about accuncpure that we can't yet explain. Certainly it's not in the same fantasy league as homeopathy. It might be cheaper and quicker than trying a private physio if your GP won't/can't referr you to a physio.