nauseated Belgium

Lately my 6 year old Belgian sheepdog licks and shakes her head during the night as though she is nauseated. She has had periods of time her whole life when she'll regurgitate in the early morning, but this has seemed to come and go. Now it seems she is feeling ill almost every night, although not always throwing up. Her appetite is good and her energy is usually good too. We've had her on tagament and pepsid per the vet and reluctantly are scheduling her for an endoscopy. Is there anything that anyone can think of that this might be?
Thanks for whatever information you can offer.
Worried dog-mom

Not to second guess the vet - but how often do you feed her?

Dogs who are fed only once a day often have a problem with vomiting. Two or three smaller meals a day is advisable.

I agree with LR smaller meals is best.

Maybe a simple xray will show a problem with the traechea.

It could also be post nasal drip, just like you and I have.

Does it happen more in the winter? And maybe during polination season?

Try a humidifier near the area the dog sleeps. Sounds like PND to me, but I could be wrong.