Vaginal disharge and swollen lips

I am a 16 year old girl who is experiencing problems with my genital health. The last time i had sexual intercourse was approx 3 weeks ago with a past boyfriend. After sex my vagina lips swelled for about 24 hours and i gained a water infection which iwas treated for with antibiotics. The water infection did clear, however days later i started to itch down below. It has been 4 days it is still very irritable. My discharge is also extremely heavy - almost as if i am ejactulating - and it can also be thick and white which is extremely worrying! I've had chlamidia tests recently which have come back negative but i was wondering if this could be a sign of any other sti or infection, and what i would have to do in order to treat it.