It seems there might be a lot going on with the structures in your neck. I’d suggest you to find an independent experienced radiologist and go through those potential findings with him/her trying to figure out the possible source(s) of the symptoms. I am obviously willing to share anything I find while investigating my own health issues, but that’s all I can do - I am not experienced in internal medicine or similar areas, and my knowledge beyond certain narrow field is very limited if not possibly misleading.
Also, one of the websites used by freelancer professionals (including radiologists) to get work is Fiverr:
You might want to look for some specialist there to properly discuss the whole big picture too.
As for enlarged IJV, I’d suggest you to look into the TOS - thoracic outlet syndrome, or other possible compressions of the veins going “down” to the heart.
One more observation is that it seems your thyroid cartilage has some growths/calcifications, maybe they are the structures irritating some nerves causing the pain?
