What Causes Brown Vaginal Bleeding, Nausea And Dry Mouth?

So my period started on Feb 10th and it finished in 7 days and u kno its still going after that with brown blood and thats normal to me cuz it happens all the time so right after that finished I had sex on the 18th of Feb around 4 or 5pm and my partner gave me plan B around 8pm and then he took me home and I went to the store to get alcohol and I forgot all about that I had took the plan B and then i realized after i had finished all the alcohol will the plan B work still so I called my bf and asked him and he said no it won t work but he wasint sure hisself so. A week later I been experiencing pregnancy like symptoms, I m not sure what day it was cuz I just thought it would go away and not worry about it but it last for A week untill today still I m having these symptoms sore breast, cramps, brown discharge, nausea, I did have a little headache but it didint last long I have been having a little mucus not fought but just mucus in the morning and dry mouth.and i seem to see a change in my discharge it went from brown to a really dark red mix with brown. I wanna kno if I m experiencing pregnancy symptoms or not thanks.