Does White Sore In The Vagina Indicate STD?

I am an 85 pound 33 year old. After intercourse I usually get very sore from chafing for a couple of days. I noticed that I have a white sore in my vagina. It is very tender to the touch but not itchy. I often get cancer sores in my mouth that are quite painful and that is what it looks like. Is this a result of chafing or could this be an STD???