Could this be a sighn im pregnant? HELP!!?

Hi there.i recently started taking birth control on the 14th on the 19th was the last pill I took.also I had unprotected sex that same day in the night he cummed in me. I didnt take my monday and tuesdays pill,but I took wednesdays pill.idk if I should start a new pack or just keep on drinking them.anyways thats not my question.on thursday morning I went to the restroom and I had a brown stain on my under wear,then I started cramping a little bit and bleeding but not bright red how I usually get it,its kind of pinkish brownish.how could I get my period again if I just had one not too long ago on the 8th thru the 13th?! Could this mean im pregnant? Or implantation bleeding? Im confused.also im very nouseouse this morning and woke up with a bad stomache pain.please help.im not trying to have another bby!! And its tooo early to have symptoms!!