Hi @Dizzy!
Welcome to our forum. I’m glad you found us. I’m really sorry for the lack of help you’ve had getting a diagnosis & especially for the several recent appointments that were cancelled by the doctors. That seems to lack professionalism especially if rescheduling wasn’t offered in each case.
I can’t say for sure that the head pressure & dizziness when driving are possible ES symptoms, but if you do have vascular compression, the stress of driving, your head position/overall posture in the car could be what exacerbates those symtpoms.
I’m more concerned about your Horner’s Disease diagnosis as that can be indicative of internal carotid artery (ICA) compression which can be caused by an elongated styloid or calcified stylohyoid ligament. The feeling of something stuck in your throat is often caused by an irritated glossopharyngeal nerve, & the coughing by an unhappy vagus nerve which also helps regulate body temperature, but there can be other reasons for body temp inconsistencies. Facial asymmetry, though rare, has also been seen w/ ES, but I’m not sure of the cause - perhaps the facial nerve is being compressed or irritated. The nerves I mentioned are among the 7 cranial nerves that can be impacted by elongated styloids &/or calcified stylohyoid ligaments & which cause the symptoms often used to help diagnose ES. The internal jugular vein (IJV) & ICA can both be irritated or compressed by the the styloids/s-h ligaments, as well, which adds another dimension to already uncomfy & hard to diagnose symptoms.
I had an upper endoscopy prior to my ES diagnosis because I started choking on my food when I ate. Mine also came back clear. I never did have the sensation of a bone or something poking me in the throat.
I’ve had tinnitus in my ears since I was a kid, though I wouldn’t describe it as wooshing, & thought everyone had that. It wasn’t until I became an adult that I learned it’s not normal. 
There is something called Middle Ear Myoclonus which is caused by spasming a couple very tiny inner ear muscles. This could be what’s causing the fluttering sensation. I have MEM of my stapedius muscle so I hear a clicking sound when it gets going. I learned that the facial nerve innervates the stapedius so connecting the dots, it makes sense that could also possibly be related to ES. Here’s the first link that came up about MEM. It purports that both the stapedius & tensor tympani work together to cause MEM, but my ENT told me it’s one muscle or the other, & the sound/sensation caused by each one is distinct so the muscle in question can be diagnosed via sound/sensation. Middle ear myoclonus: Causes & treatment | Miracle-Ear.
It’s really sad that you’ve been so put off & rushed by the doctors you’ve seen that you haven’t felt comfortable sharing all your symptoms. That is also not good medical practice in my book, but too many doctors don’t make the time nor offer the consideration they should for their patients, especially patients w/ more complex symptoms.
Your symptoms do sound like they could be ES, and yes, those symptoms aren’t necessarily caused by a tonsillectomy. The youngest member on our forum began having symptoms at age 8. He’s 20+ now.
In addition to tonsillectomies, in some cases, ES is suspected to be hereditary, in others it’s thought to be caused by a jaw, neck or head injury. It can possibly be hormone related (parathyroid dysfunction), potentially posture related, & there’s even speculation that having had braces to straighten the teeth could cause ES by changing the position of the jaw joints thus putting excess pressure into the neck.
These 2 doctors on our Doctors List are in your state & have both had positive reviews on our forum. I would recommend getting an appointment w/ one or the other (whomever you can see first!) as you’ll get further w/ a diagnosis that way. You can use the search tool to find posts about them. Just search their names:
•Dr Andrew Patel, PDX ENT, Pacific Northwest Portland 503- 222- 3638 (Otolaryngologist) https://pdxent.com/
•Dr Joshua Schindler, 3303 SW Bond Ave OHSU Northwest Clinic for Voice and Swallowing, South Waterfront Center for Health and Healing Building 1, Suite 15, Portland, OR 97239, Has apparently done 18 sucessful surgeries, intra-oral and external.
Finally, here are the links to a couple of very informative posts our moderator @Jules wrote which will give you more thorough information about ES symptoms:
I hope all this info is helpful!!