Severe neck pain with difficulty swallow

I have been smoking for last 4 years and before 4 months I have got sudden neck pain with difficulty swallowing. I went to ENT specialist he asked to make the USG scanning and after that he told nothing to worry about by seeing the scan report. Took all the medicine and consulted even orthopedic doctor as well but no use. When I turn my head up and down or right or left I feel a severe cracking sound with pain. Even made blood tests and also TB tests all are negative. I feel like lump in my left neck and asked the same with ENT specialist, he said there is nothing to worry. I have attached scan report of two different months. Please advice me the exact cause and what steps to be taken to examine the problem. Thanks