Hi Wavyglandbles,
From what you wrote, I believe that a new physio visit is needed, with particular attention on physical examination. Symptoms behaviour during examination are key to better understand your case. Burning sensation would indicate nervous structures involvement and as you have been suffering from this situation for a long time, I think that investigations (ultrasound scan/electromiography/electroneurography) may come handy in order to rule out/in conditions.
This is only a personal advice over the internet, clinical examination is key.