Took plan b pill like 1 week and half ago and had spotting 5 days after and yesterday started feeling like i have to pee after going to the bathroom and the feeling doesn't go away but it's not painful. can it be early pregnancy symptom? plan b fail?

"Spotting five days after a "Plan B" pill" is common secondary to the withdrawal effect from the drop in estrogen associated with stopping the extra source of estrogen in "Plan B". Wait until your expected period is five days "late", and obtain a "home" pregnancy test to be certain about pregnancy, since "Plan B" is not 100% certain to be effective in prevention.