Cystitis is inflammation of the urinary bladder. Most often is it cause by the bacteria E. coli. In can occur from improper hygiene and anal intercourse. This bacteria is cleared from the urinary tract after about three days of antibiotic therapy (courses of antibiotics are given for ten days to help minimize the chance of recurrence).

Your symptoms (to me, anyways) sound more like a yeast infection, which is caused by the fungus Candida albicans. Like E. coli, it is apart of natural flora living in the large intestine; it can be transmitted by both anal and vaginal (if C. albicans has colonized the vagina) intercourse.
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