Yeast infection or what?

Over a week ago I had sex with a guy that is more well endowed than any other guy I've been with. I was in incredible pain during the intercourse. He also used a condom, which was the first time one was involved with me for several years. They are uncomfortable for me. Anyways my vagina was sore for days and now incredibly itchy. Sex continues to be painful, I have swelling esp after sex, and now I have a little bit of thick discharge which seems as if it may be light yellow but no smell. I began to use Monistat and it seems to be helping. In that case, can I just assume this is a yeast infection?