pain outside & in my vagina, light discharge, and itching.

I am a sexually active 22 year old. My period is usually regular, middle of the month. My period came, what seemed to be early, the beginning of September & lasted nearly 2 weeks (brown to red, never heavy flow, painful cramps.) My cycle normally lasts 4 days, not 2 weeks. The last 2 days of my so-called period my boyfriend & I had sex. Other than natural discharge from arousal, there was faint brown (from period.) This all happened this week (9/11-now). The past 2 days I've been experiencing pain outside & in my vagina, light discharge, and itching. It's unbearable & I lose sleep. I figured it is a yeast infection & bought Miconazole last night, used it, woke up this morning & have pieces of red fleshy tissue each wipe when I use the bathroom. The pain resumes. I'm miserable, worried, not sure what is wrong. We have unprotected sex regularly & I do not use birth control. I pee frequently & when I have very little urine inside, it feels full. I'm scared about the tissue & pain.