Thick saliva/mucus buildup

Respectful greetings.
I’m asking for help, if anyone can offer some, or at least some comfort. I’m 85 years old and I’m struggling with constant excess saliva—or something like it. It’s been five years of this misery; I’m constantly spitting because swallowing just isn't an option. It’s thick, sticky, and moves like egg whites. I spend my days pacing the house or sitting there with a juice box just so I have something to spit into.
I went through a gastroscopy, and the doctors claim everything is fine. They tell me I should be able to swallow my own saliva, but they don't understand. My throat feels like it's sticking shut, like I'm going to choke. I've noticed certain foods trigger it. At first, it was milk, so I cut out all dairy for two years, but it didn't help much. Now it's potatoes, dough, rice, pork, beef, deli meats... even sweets and fruit. Oranges, tangerines, kiwi—forget it. Even a glass of Tropicana or any kind of juice makes the saliva flow so heavily I can barely function.
My stomach doesn't hurt. I had a perforated ulcer once, but that was handled by specialists at the hospital years ago. This saliva issue is a different beast entirely. I try to drink water—two liters a day—but even that is a struggle because the water seems to thicken the saliva further, making it even harder to swallow. When I spit it out, it looks like clusters of tiny, dense bubbles, almost like grapes. Sometimes it feels like it’s even sticking to my eyes.
Please, if anyone has any answers, I am desperate. I've run out of people to turn to. I would be eternally grateful for any help you can provide.

Ma'am, I happened upon your post. I hope you are still holding up well.

I went through an identical gauntlet with doctors—dealing with a situation nearly indistinguishable from yours. While I cannot be certain if our underlying causes are one and the same, you might find my experience useful.

First: I have zero remaining faith in the medical establishment after this ordeal. Frankly, I find it hard to believe those amateurs who performed your endoscopy were even telling the truth. It is highly probable—entirely plausible, actually—that the issue is gastrointestinal in nature.

My saliva became thick, viscous, and excessive; I could barely speak.

1. I had my entire mouth treated—based on the claim that bacteria could cause such symptoms. That was nonsense; bacteria might increase volume, but they won't change the consistency.

2. Sinus scans = nothing.

3. ENT specialist visit = nothing; told me everything was "normal" and that it would simply "pass with age."

4. Consulted "renowned" specialists in oral medicine = they prescribed various useless herbal teas. Absolute waste of time.

5. Nuclear medicine imaging for salivary glands = nothing; the doctor’s brilliant advice was to just "buy some gum and call it a day."

6. Blood work = perfect.

7. Stomach ultrasound = nothing.

Eventually, H. pylori was discovered and treated—but the core problem persisted regardless.

Ultimately, the only option left was a gastroscopy. Since I have a violent gag reflex, I paid to have it done under full general anesthesia. They diagnosed severe gastritis, a hiatal hernia, and GERD—acid reflux that can indirectly cause thick saliva in certain individuals. I am currently on medication and feeling significantly better.

The catch is that for some people—myself included—the reflux is silent; according to a certain "top-tier expert," the acid seeps through the sphincter pores without any noticeable sensation.

A subtle form of madness.

After everything I endured, I am simply grateful that, amidst a sea of incompetence, I finally encountered a true specialist. Whether you have been lucky enough to find one—assuming you are still sane after your own ordeal—is anyone's guess. However, based on your description, I suspect there is a definitive gastrointestinal issue at play, regardless of whatever nonsense was reported during your endoscopy. My advice? Seek a second opinion privately.