[anonymously]

She is old, I don’t want to upset you, but it may just be her time. You could take her to an emergency veterinary clinic (no appointment needed).
Let them run some tests and see what they advise regarding aggressive treatment vs keeping her comfortable. Or call her regular vet, if you think that would be helpful.

If she is nauseas, forcing her to consume things might make her even more uncomfortable and prolong her agony.

PS: I hope I am not coming across as harsh, I understand your distress and I wish you and your dog well.