24 yrs old. before most periods, i experience painful urination & urinary frequency/urgency. history of irregular periods. never been sexually active.

See your doctor: Bladder & pelvic floor symptoms often are worse in the second half of the cycle. Some women have endometriosis in the bladder, which can cause the symptoms you describe. Get a workup for bladder infection, and if this is negative, get an evaluation for overactive bladder. If you are a smoker, this may include a cystoscopy to look for bladder tumors, although rare.