I am 21 years old and I have a boyfriend. He is 24 years old. We are in this relationship for 1 year now and we have a healthy sex life. I will have to admit here that I did have sex with my boyfriend just once and from that time onwards my problems have started. Two days after I had sex I am having a vaginal infection which is hurting me very badly. One of my close friend’s is saying that I might be infected with a STD. I want to know from people what a STD is anyways. Can anyone give me all info about this sexually transmitted disease and symptoms?