Excess Salivation

I've had what I believe is excess salivation for 9 years. I have seen a few ENT's, an oral pathologist, and a few endocrinologists, in addition to my primary care physician (PCP).

The first ENT found no problems and insisted it was psychogenic. The second ENT tried a few meds on me, anticholingerics, to see if it would help dry out my mouth. I also tried some meds with my PCP, one being glycopyrrolate. None of them worked, but I was only on a fixed dose for a limited time (2 weeks each med). The second ENT also did a GERD test on me, which tested negative. The third ENT, which I saw recently, noticed my tongue shaking and suspected it was ALS. He referred me to a neurologist specializing in ALS, but I didn't follow up as my tongue would be still when I just relaxed my jaw area. Also, I didn't see how tongue shaking tied in with the excess salivation. I saw an oral pathologist a few years ago, and she couldn't find anything abnormal, so didn't do any tests.

I also saw 3 endocrinologists recently, as I suspected a hormone imbalance might be the cause. The first tested for a few hormones only, two of which were low - testosterone and prolactin. The second endo refused to do a full endocrine panel on me, as she couldn't think of any hormones that would cause my symptom. She blamed it on anxiety in the end. The third endo, who I saw today, said there was no such thing as a "full endocrine panel". She also couldn't think of any hormones which would cause excess salivation. So at this point, I am stumped on what to do next. I keep asking endocrinologists for a complete endocrine panel, but I never get one. Maybe I am wording it wrong?

I have been dealing with this for 9 years, so my bottom lip is no longer in the shape it was normally. I'd say it's around double the thickness, droopy, and loose (not tight). As a result, when I close my mouth (which I have to all the time or else I drool), I actually have to lift the bottom lip slightly higher than normal to touch the upper lip. Maybe this also causes more salivation?

I have had bruxism (teeth grinding) for about 13 years, so maybe this is another cause? I choke on my saliva when sleeping on my back, so I have to sleep on my side. I also can't talk for more than around 10 seconds at a time without having to pause and swallow. This is what makes me believe it really is excess salivation and not (or perhaps not just) inadequate swallowing frequency.

The causes can be one or more of the following: ENT, neurological, endocrine (hormone-related), dental, or just the shape of the bottom lip. I apologize for the long post, but wanted to be as detailed as possible so I can finally get to the bottom of this. I'd greatly appreciate any advice or speculations as to what may be causing the salivation. I even considered lip reduction surgery, but don't want to find out the hard way that it doesn't alleviate the salivation after I undergo the procedure.