All the problems of mouth throat and nose are intr related. In your case there seems to be a nasal problem.
Whatever the problem is, the result is the same. you tend to get an overgrowth of anaerobic bacteria that change the micro flora of your mouth. In other words the anerobes kill off the aerobes.
All mouthwash on the market, are not strong enough to reverse this trend. And if they could they would cause more problems. The bacteria that have overgrown, have a major function, they stop Candida.
So if you killed them off, and did not replace them with the right bacteria you stand a chance of getting a candida infection instead.
The Grapefruit-Seed-Extract also would not be strong enough. What it might do is remove one type of bacteria, which would allow more of the bad guys to come in. But it would not kill all the bacteria.
The KFORCE system, uses a prescription strength mouthwash made by Colgate to knock down the bacteria, and then replace it with the special BLIS K12 bacteria. By the way all the probiotics being talked about on this forum, are not good mouth bacteria but rather probiotic bacteria for the stomach. They will not colonise the mouth successfully so will not work.
You can order from the online New Zealand chemists. This is a 3 days intense course. Also you need to sort out your nasal problems.