Hey
@Russell Grimes.
I'm glad you posted your symptoms and your post about Eagle Syndrome. I also have many of those same symptoms except the clicking in throat and current ear pain. My pulsatile tinnitus is on my right side, sometimes sounds like it's in the back of my head, and I have normal tinnitus on my left side, all starting at the same time (I think due to the erratic blood flow caused by the pulsatile tinnitus Issue). When I first got it, it sounded like an electrical storm, now it just sounds like pulsing static. The pressure in the back of my head is the worst, like you said, those loud 5-7 seconds of extreme pressure and whooshing when standing/bending over/any stressful event.
After a series of doctors, I was able to get recommended to a Neuroradiologist and had to get a CT/A, MRI/A (on at least a T3 Tesla MRI machine because normal MRI machines are not as clear), Lumbar Puncture, and Neuro Angiogram to figure it out. They were able to find bilateral high cervical internal jugular venous stenoses, with external compression from the styloid processes, and blood rerouting through the condylar venous systems - causing so much pressure. They also found a right sigmoid sinus diverticulum however they believe the compression of the jugular vein is the issue. All my other doctors missed it on previous tests, it wasn't until I found a good Neuroradiologist also called Interventional Neuroradiologist that I was able to get a potential diagnosis. I'm still dealing with it now so I understand how much it hurts the quality of life, but know you are not alone, and you will get through this.
Mine is reactive to many different things, and I was wondering how reactive is yours? Such as if you move your neck side to side or up and down, does it increase/decrease the noise level? Are there any areas on your face or neck that you can push to make the noise go up or down (especially below your ear area)? You say it's reactive when you get up from sitting and standing, how about if you hold your breath deep for 20 seconds, then let out, does that cause any pressure or noise change? I truly believe once you find a good Neuroradiologist they will be able to figure this out, make sure you ask your doctor or Neurologist for some references/referrals - normally the best ones work at university hospitals.