Hi. On The 28th Of July My Boyfriend Stuck It

Hi. On the 28th of July my boyfriend stuck it in and did about 3 or 4 strokes but didon't bust. The very next morning I took plan b becuase I was scared of getting pregnate. I wasn't supposed to start my period until around the 18th but today I had a little bit of blood so I thought that I started and then there was some brown discharge but now it is gone and I have never had this happen to me and my period is normally always on time. Please help I am terrified