re: Cold sore remedies...any way to stop one once it has already gotten going?

A review cited some studies showing that lysine supplementation can decrease herpes simplex cold sore outbreaks and reduce healing time.[15] However, an authoritative Cochrane Review published in 2015 concluded there is insufficient evidence that lysine supplementation is effective against herpes simplex virus; it has not been approved by the FDA for herpes simplex suppression.[16][17]

^WIKI

"I am herp free....never had a cold sore"

Good for you but that doesn't mean you don't still have the virus laying dormant in your nerve endings. According to the CDC anywhere from 50% to 80% of all Americans under the age of 50 have the Type 1 version of the virus in their bodies. However, many who do never get a cold sore. The reasons for this have to do with how sensitive the skin around your mouth is to the sun/UV rays, dry skin, sensitive skin, and other factors. The Type II version (that causes the true herp (genital version) is much different and much less common thankfully. The danger is that the Type II can be spread via the Type I if there's contact with the privates during an active case of Type I. It'seems extremely contagious so the mouth (or even the fingers if they have been touching the mouth sore) of someone with a cold sore can have no contact whatsoever with someone's privates. That's the main way Type II can be spread.

News flash, simplex 2 can also be on your lips.