This is likely a herpes virus, so either an antiviral or Lysine will work. If you choose to use the Lysine, I would suggest that you start taking 8,000 - 9,000 mgs daily, split into 3 doses. This is the routine that I follow when I have a cold sore start. I stay on the higher levels until the sores start to heal and then slowly lower it back down. I stay on about
6,000 mgs daily anyway to keep my EBV and herpes viruses under control.
Lysine blocks arginine - arginine is what encourages/allows these viruses to replicate easier essentially.
I also like to use a product called Herpecin. It's a lip balm for those with cold sores:
www.herpecin.com/ I have nothing to do with this company, other than finding this product helpful. It just helps keep the crusties down to a minimum on those cold sores.