Yesterday My Boyfriend And I Were Having Sex, We Have

yesterday my boyfriend and I were having sex, we have done this only twice. And now, today my vagina is very itchy and it stings a little bit when I pee. There is no abnormal discharge. When my ex and I had sex this never happened, so I don't know what is going on. Only a few weeks ago I had my first yeast infection and I masterbate a lot. Should I stop masterbating or do I have a sexual disease?