TMI Help needed

So I have a situation, and If anyone has this before please reach out . So I did have intercourse with my ex , 1 day before my cycle was due to go off . (Yeah nasty I know ) anyways I end up douching for the first time in my life a day after. A few days later I started to have a yellow smelly discharge . I literally went to the dr to get a std check everything came back negative , he gave me antibiotics just in case . Going on a week symptoms were still there . I went back for whatever reach they tested me again NEGATIVE . Please what is going on with my body 😔😔😔