What could cause throat pain (above & to right of adam's apple) when tilting head back? have had lump there when swallowing but mri showed nothing.

ENT+GI docs to check: If something is in the throat or neck, an ear-nose-throat doctor and a gastroenterologist should evaluate. The doctors can decide if it's worthwhile to do a cine-esophagram or other swallowing study to see if something happens during swallowing. Sometimes, nothing can be found at the present time, but rechecking later may locate a problem, especially if the problem has grown big enough to show up.

A lump: in that location that occurs only when swallowing could indicate an outpouching of the esophagus(diverticulum). An MRI may be negative because if you are not actively swallowing the diverticulum may be collapsed or completely reduced. These can be diagnosed with a tailored barium swallow/esophagram or endoscopy.