dear Thanks for contacting with your health concern. i. going by your gender [female] it must be remembered that female is more prone to UTI than men because of the shorter urethra and smaller distance between the anus and urethral opening. [as such UTI bacteria may also reach the anus [ improper cleaning after sex] and then migrate to urethra and bladder leading to infection], so it could be the cause. ii. Sometimes irritation from soap to the urethra may allow fluid to leak from the bladder and cause infection. [as the area is sensitive] 2. It is advisable to visit your primary care doctor or Urologist for - Urinalysis & Urine culture [of both] to identify the cause or bacteria causing the infection and if the reason is UTI he will prescribe appropriate antibiotic accordingly to resolve the infection, till then stay hydrated and avoid unprotected anal sex since it can cause urethritis, prostatitis, and bladder infection in males also.