HELP!!!! Implantation bleeding??

Hi guys need a bit of help understanding the difference between implantation bleeding n AF. Ok so my confusion is that I thought I had my visit from AF 6-5days early this month after having sex with my SO. It started a few hours after having sex but it was very light n was stopping and starting again over the 2days now I got brown spotting for a couple of days after that witch I never get. Been getting twinges in my side and stomach n also some back pain over the last few days as well. Have been feeling really under the weather as if am getting a head cold and also feeling dizzy and sick witch is getting stronger. AF was due on Friday there? Should I go see a dr about this. I never knew anything about implantation bleeding till someone suggested it?