Nate,
Why are you using Peridex?
I'm somewhat guessing of course, but:

Peridex is an anti-gingivitis treatment and gums infected with gingivitis get sores and bleed.

Do you have periodontal issues (receding gums, excessive plaque, etc...). From here on you will need to get your teeth checked and cleaned every three to four months.

I'm surprised you are on Peridex, I thought it was alcohol based and alcohol based mouthwash isn't normally recommended for OC patients / survivors. So, there must be a medically necessity.

Consider getting a water-pic. Now that you have quit smoking the Water pic should clear up your gums and keep them healthy. Use it a couple times a day with warm water and a quarter teaspoon of 50/50 Salt & Baking Soda. 'BUT' during radiation you will want to keep the pressure real low.

I have never heard of OC-SCC growing as fast as you are imagining. Since your tumor was removed, the oral radiation will be going after microscopic cancer cells that would need many months to multiply into visible a tumor.

I don't know why your stage was up'd to stage IV, but lots of us were staged at IV and it doesn't mean a lot regarding being cured. A stage IV OC-SCC isn't necessarily the same as other stage IV cancers. It is combination of adverse TNM and invasive characteristic that really matter.

Knowledge is power. Study and Print out the TNM Staging info at http://www.oralcancerfoundation.org/facts/stages_cancer.htm and discuss it with your ENT or RO - they can explain exactly what was found that led to their change in staging and the implications.

Remember, "Tomorrow is the first day of the rest of your life" and you will only get to live it once, so always try and make the best of it.

OK, I know in a few weeks there will be some days that living once will be more than enough, but even those are a unique journey of a life time, so let the quest begin - stand up to cancer and live!

Tomorrow I have a 20 mile bike ride around beautiful Sail Bay and Mission Beach on my vintage Austro-Daimler Vent Noir - can life really get any better? I'll be around to let you know