My love for this natural remedy is growing as the years go by... not only is apple cider vinegar effective for treating tummy upsets, we've recently discovered that when taken every 30 minutes, it stops a sore throat dead in it's tracks! I've used this method successfully over the past 6 months and find it to be much more reliable and effective than using oregano oil. It's less expensive, also - so a win all around :)
As to dosage, I usually take approximately 2 TBSP in a half cup of water. When taken at the first sign of a scratchy/sore throat, and repeated faithfully every 30 minutes, relief will usually be felt after just a few doses... I don't like the taste of ACV, so I plug my nose and drink it down quickly. The short term discomfort of the taste is preferred over getting sick, so I suffer through it :)
Sore throats are usually the first sign that a cold/influenza is on the way and I've noticed that people will spend a lot of money to try and ward illness off. I'm encouraging you to give apple cider vinegar a try ~ it is highly effective and very inexpensive.
Let me know if it works for you!