Well sometimes pain can be difficult to treat .... A gastro esophageal reflux (gerd) often typically presents in a similar manner and not easy to diagnose even after an endoscopy
... I think u should go for a trial of proton pump
20mg a day ) for about 4 wks before u undergo anything more invasive.
An local injection would only work if it is a musculoskeletal pain
.... But since it hurts when u swalow something i think it is something gi.... My advice avoid the injection.... Ps : even if it is musculoskeletal go for non nsaid painkilllers like tramadol