Vaccinated for what? Hatcheries only vaccinate if you pay for it.
If you haven't gotten the Nutri-Drench I'd really suggest you try that over homemade remedies, since your chick is still doing poorly.
If you can get Poultry Nutri-Drench it's the best pick me up/stress treatment for chicks. If not, molasses is one of the main ingredients in Nutri-Drench so you can thin that out with some water and directly give the chick a few drops.