need some advice! please

hi i just would like some advice, i am on the pill and when i finished 21 days i had sex twice before my period, then i got my period it was very light and on the last day i got a bad pain in my lower tummy and was bloated for a few hours the next day period was gone, so had sex twice again before starting my pill the next day since then the past two weeks i have been feeling very sick slight cramps here and there also the feeling i have my period i have been still taking the pill i done a test two days ago said it was negitive but i cant shift this sick feeling and i have been tired but i put that down to my one year old son the sicking feeling it comes and  goes throughout the day i havent taking my pill today as i am unsure what to do i went to the doctor but he just gave me tablets for cramps but i was only gettin slight cramps now its two weeks and i still feel no better, can anyone give me some advice please thank you