Missed Periods. Any serious concern?

Hi, She had periods on 14th Feb last time. Then we thought on 14th March, it is safe to have sex as it is just before period starts, we didn't complete the intercourse, we did on 16th, 17th and 18th March (as it was our first time, we didn't do complete sex, but pre-cum may have entered vagina). But now she didn't had any periods since 14th Feb, she took I-pill then on 18th March, as currently we do not want pregnancy. So I wanted to know is there chance of pregnancy? Today is 22nd March now. Also she is having very little blood on putting napkin in vagina even today, we didn't had sex after she took I-pill, and she is also having burning pain in her vagina, also there is small swelling near her vagina on one side. Is there any serious concern? Eagerly waiting for your reply Thanks.