Bladder pain. Infection? am i pregnant?

I took plan b twice last week (if that matters), i got my period about april 4th. mine is pretty regular. the day before yesterday i had to pee but there were no bathrooms available, i held it in until it got really painful. yesterday (monday afternoon) i began to have pain. my bladder feels full but when i pee it's only drops. it doesn't hurt or burn to pee and i pee pretty normal it's just the annoying feeling of constantly needing to pee and right now, unbearable bladder pain. if feels as if i've been holding it in for a long time. it even hurts to walk now. and i have an odd pain added on my lower stomach side. this is aside from the bladder that feels like it's right below the lower stomach. straight down the belly button. today, i noticed another period. it's not blood in my pee, it's period looking blood, like being caught in a tampon. can this be a result of the pill? is it a bladder infection? am i pregnant? i'm 20 years old, about 110 pounds, 5'1,