I found this procedure of Home Cold Sores treatment using Apple Cider Vinegar and Salt. I have not tested it myself. But this procedure is believed to be sent in by a real cold sore sufferer. Decide yourself whether you want to try this or else seek medial advice. The procedure is painful.
1. Slowly and gently open the blisters/sores with a needle
2. Gently apply apple cider vinegar with salt.
3. Wait 20 minutes and gently apply lemon with salt until the stinging pain stops
4. Apply toothpaste on the sores and leave overnight
5. Next morning apply Vaseline, followed by more vinegar and salt.
Repeat the process until the cold sores are healed.
After that dab with milk
In 20 minutes use rubbing alcohol
In 30 minutes cover it with finger nail polish remover
Finally crush a clove of garlic and hold it to the sore. (Yes, it stings)
By this time the sore is gone and you can cover the redness with lip stick.