I have an elderly female pug. Usually very high spirited. For the last three days, she has been disinterested in food, eating only a few bites. She drinks a lot of water, then throws it back up.
Just now when I got home she drank a bunch of water again, threw it up again. I am getting worried. We were told it was probably bloat and to treat her with gas meds to alleviate. Doesn't seem to have made much difference.

When was her last vet visit? Elderly pets need exams at least twice a year. I'd make an appointment before she becomes dehydrated.

Thanks for the reply, she saw her vet six months ago, we just moved here and has an appt tomorrow. Just wondering if I should go to er tonight...

While intestinal parasites would be an easy fix, it is impossible for anyone to diagnose online.
Given it is now morning, if you did not take her to the emergency vet, make sure you keep your appointment, if you have grown more concerned overnight call them first thing this morning and ask (insist if you must) for an earlier appointment or ask to be worked in.
Elderly dogs go through the same physical changes that we humans do, diabetes, renal disease, etc.
Good luck and I hope you get her sorted out.