You may be reacting to your toothpaste.

Triclosan in many pastes and soaps is
Highly controversial right now. It may be
Removed soon. If you Google it you
Can read more. There are studies about
It on PubMed as causing mouth irritation
and more.

I think CAPTAIN OBVIOUS might say something like, "That's a clue! ....And a starting point." Unfortunately, the captain isn't always very astute at deduction or directions...

What happens if you fast in the morning? Does the burning still start at 9 am?

Apologies if you've been down this road, but I'm a little hypersensitive to the possibilities of triggers right now due to some things & discoveries my DW is going through.

Doc

i am on Gabapentin too. The therapeutic dosage should be at least 1800mg a day. Even with this dosage, I dont get total relief but at least some. If and whn you decide to up your dosage, dont do it abruptly. It has to be adjusted gradually....please consult your doctor.

Whatever it is, I think the recommended dosage for gabapentin (and some other things) is/may be too high. The few times I took gabapentin for my PN, 100 mg. was enough to stop the burning for up to 24 hrs. Back when I tried it for chronic pain I couldn't complete the upward taper—it fried my brain without providing any therapeutic effect (and there's some question that the damage was permanent).

I realize I may be the outlier, but I learned from those experiences and others to err on the side of caution when titrating medications. These recommended therapeutic dosages are determined by studies (Phase II, IIRC) done by Big Pharma (whose purpose is to sell more drugs—not less).

My DW also does fine on lower doses of gabapentin—usually 100 mg. (for fibromyalgia and/or cervical stenosis) and rarely (couple/few time a year) up to 300 mg. with bad flares. Since being on an elimination diet, she's taken almost none, and has been able to reduce other medications to a trickle as well...

We're all different, and 1800 mg may be the magic number for many/most—I just think it makes more sense to start low and stop when efficacy is acheived rather than assuming everyone is the same and scarfing down fistfuls of nostrums....

Doc

I had been on a total of 600 gabapentin and couldn't tolerate any more. I don't think it even helped but is read about gralise 600ER and asked my neurologist if I could try it. It eased my burning to a tolerable level. I asked her if I could add the 300 ER gralise. She told me to take one of them in the a.m. The other at dinner. I have started the 600 at breakfast and will see if this helps the burning which is at it's worst in the mid afternoon. The slow release of this May keep the gabapentin in my system. Will let you know how this works.

Benfotiamine, a form of Vitamin B-1, helped me the most. It may be hard to find in local health food shops, but readily available on line--iHerb has it. When I wake up in the middle of the night with burning legs, lotion with methol helps the most to get back to sleep. (Cold takes precedence over hot.)