HELP! Plan b symptoms or Pregnancy?

TMI! Hey guys so back in September 12-18th I had my period and on the 20th I had unprotected sex with my s/o. I took a Plan b right away and today I saw some brown spotting which has never actually happened to me. All day I’ve been bleeding like if I was on a light period and I even have symptoms I would usually have during my period. I have 11 days till my next period, can I please get someone’s opinion. I’m a little stressed and this has never happened before. Is this normal? Thank you!