If cause of a chronic sore throat can't be easily determined, can it persist for months/years/indefinitely? been through so many tests & no answers

Chronic sore throat: Chronic sore throat most commonly due to lingering virus; post-nasal drip (see ENT if have not already: they can check your CBC, ESR, ANA to be sure not internal inflammation; allergies (can be environmental or food sensitivities: ie even though not "proven" would try gluten free diet for 3 months & focus on eating a low-inflammatory diet to see if this helps if all other tests have been normal