Pill advice???????????????????

my period began on Dec 8th and i started on Marviol birth control pill.. anyways stomach hadn't bn feeling too goo over last few days and yesterday had 2 episodes of diahreha within 10 mins so took immodium.. felt grand after it.. This happened at abt 4pm yesterday.. I took my birth control pill at 8pm last night.. My boyfriend and i had last night.. We didn't use a condom.. just wondering if i need to take plan b or should i be ok..