Hi. I v had a cold sore on the left side in the back of my throat which is something I have from time to time. Iv used an anti bacterial to gargle with and it seemed to go away in the normal way that it always does, until now, a few days later it has changed and it seems like it has started to eat away a little bit of the skin the the cold sore was on to beginn with, like it s created a whole where the original cold sore was. Any help on this would be great.