These are symptoms of vascular compression which you seem to have in spite of normal length styloids. I hope you’re able to get a referral to Prof Elliott & he’s able to help you!
Here’s a paper which has a lot of information about IJV compression but mostly related to elongated styloids, but it would still be good for you to read it. There have also been a couple of long webinars about “vascular outflow obstruction” which you can find on YouTube:
I can’t find a link for the second one but it is provided in this discussion from our forum by our member @stuuke on Feb 4. You’ll need to scroll down the discussion a bit to find it. Date is in the right upper corner of each post:
The second one deals primarily with venous congestion (IJV & other veinous compressions) caused by or related to Ehlers Danlos Syndrome. That might be another thing worth looking into in your situation.
If you find icing your neck makes your pain worse, try heat. Heat does work better for some people. Ice worked best for me. 