Welcome to the community!
It sounds like your Vet is not at all an Avian Vet, because any bird that is vomiting is NOT NORMAL at all...And it's a sign that he is most-likely suffering from some type of infection in her GI Tract. When they vomit it's typically an infection in the upper GI Tract, specifically the Crop, and usually it's actually fungal, or both fungal and bacterial...The only way to help her is to find either a Certified Avian Vet or Avian Specialist Vet (no "Exotics" vets with no Avian experience or education), and they will typically take a culture from her Crop, along with doing a complete Fecal culture that is sent-out to a lab and then also do microscopy/Gram-Staining on both right there in their office and look at it under their microscope. If it's a Fungal/Yeast infection they'll be able to tell right away and they'll put her on a prescription Anti-Fungal medication, and if they also see Bacteria in her Fecal or Crop samples that are not the normal, beneficial Bacteria, they'll also put her on an Antibiotic and wait for the culture to come back to make-sure the Antibiotic they put her on is the correct one, if it ends-up not being correct they'll change it at that point...And if it's just a Fungal/Yeast infection, then she'll be good to go on the just the prescription Anti-Fungal...
As far as "home-remedies", there aren't any. The best you can do is to try to ease her upset stomach and GI Tract by giving her a daily Avian Probiotic supplement, which will also start to replace the beneficial bacteria that is supposed to be throughout her GI Tract, and that also keeps the Yeast at-bay..However, the daily Probiotic supplement will not get rid of any already existing Fungal/Yeast infection, only the correct prescription Anti-Fungal medication will do that, just like only the correct prescription Antibiotic will get rid of any Bacterial Infection...So you need an Avian Vet ASAP, before she stops eating and drinking all together.
There is a good search tool here in the forum for finding Avian Specialist Vets, hopefully someone can post the link her for you to use so you can find the closest one to wherever you live and get her there ASAP. Be sure to tell them that she's already been ill for quite some time so that they get her in right away.
In the meantime, I would hit your local Petco or Petsmart and pick-up some Avian Probiotics, either a bottle of Qwiko Avian Probiotics, which all Petco stores sell for $9.99 and comes with a pre-measured little scoop which you simply use to sprinkle the correct amount on top of her food every morning with her fresh seed-mix or pellets, or a tube of Benebac Gel/Paste and follow the directions on it as to how to give it to her each day...And at her age I would keep her on a daily dose of Probiotics each day from now on to help her immune system out and keep her beneficial bacteria high and the fungi/yeast away. I give my birds all a dose of the Qwiko Avian Probiotic every morning just as a regular part of their diet, and none of them have ever had any type of GI upsets or infections. Probiotics can never hurt them and can only help them, and in the case of an older parrot it's just a good idea anyway...
Remember that the Probiotic may make her stomach and GI Tract feel better and it may even slow-down or stop the vomiting temporarily, but it is not at all a cure or treatment for an already existing yeast or harmful-bacterial infection in her GI Tract, only the correct prescription Anti-Fungal or Antibiotic medication in the correct dose for her weight will do that, so you can't not take her to an Avian Vet for a Fecal Culture and Gram-Stain along with a Crop-culture and Gram-Stain ASAP...