Neck tightness and choking sensation. Is this due to my anxiety or possibly something else? Gp said its anxiety but not convinced, ER said the same

Anxiety. Try relaxation exercises and see if it goes away. If it comes and goes it most likely is not something pathological, but anxiety. Inhalation gives you energy and exhaling gives you relaxation. So try to extend your exhalation. You could visit dawnbuse.Com for free and get other relaxation exercises. Avoid caffeine and make sure to excercize and hydrate sufficiently.
Anxiety. You are young. Unlikely to have any significant pathology that would cause this. Assuming all tests are negative for swallowing problems and there are no spinal issues, it is most likely anxiety about something in your life.