I am a 25 years old girl, I had sex 6 days ago we were cautions use the contraceptive, a day after I feel pain outside the vagina where there's fur, then a day later I feel like wanting to urinate, when I go to the toilet only few urine came out and later I felt a small pain when I took a tissue there was few blood. and then 3 days it was serious the whole urine was red en a smell with that little pain. Can you please tell me what to do and how to prevent it, I am worried.