Hi, Thanks for trusting us with your health concern. In the current scenario, pregnancy is ruled out for two reasons. Firstly, you had the intercourse soon after your period and in the usual case, even without any protection, this is the safe period. Secondly, your cycle is protected. Now, the most likely cause for your symptom is an infection in the lower urinary tract which usually occurs secondary to a traumatic intercourse. Please get a urinalysis and plan further management. Take adequate liquids and avoid further intercourse until you are healed well. Hope this helps.