I Recently Got A White Sore In My Mouth And

I recently got a white sore in my mouth and assumed it was just a regular old canker sore and let it alone. Well I have had it since Wednesday and it is now Sunday and it is getting bigger and bigger and infected. My friend brought to my attention that it could be an std. Then I started getting brown discharge coming from my vaginal area along with lots of soreness. I am dating someone new and this all started after we had sex And messed around. Could my friend be right?