Had Unprotected Sex On The Last Day Of Periods. Feeling Dizzy, Headache And Have Blood Spotting. Am I Pregnant?

hi well i had sex on the last days of my period which was 13th and the 14th december,i had unprotected sex on both days,then 2 days after sex i started feeling sick,dizzy having headaches then 3 days ago on the 24th december i started having abdominal cramps ,and today when i got out the shower i wiped myself with a towel and there was a bit of blood on the towel with a tiny blood clot in it,not period like blood it was watery kind of blood,then i went to the bathroom and there was a little bit of blood in my underwear and when i wiped there was abit more blood,i knew it couldent be my period as my period is not due now till 11th jan,and i have never had spotting before! was this implantation spotting? am i pregnant? how far along would i be if i am?