You have not mentioned in your question the duration between the last unprotected sex and your symptoms.
If the gap is more than 10 to 15 days then the brownish discharge and cramps could be early sign of pregnancy
Small amount of bleeding could also be due to pregnancy, what is called as implantation
But if the gap is less then drop of blood in your urine could be due to urinary tract infection
, which can be confirmed by urine examination.
Brown discharge could be due to fungal infection
Hope I answered your question.