Hi I Need Your Help, I Had Unprotected Sex A

Hi I need your help, I had unprotected sex a numerous times with my boyfriend a week after coming of my period... Since then I have been feeling a bit lightheaded and sick at times, I have had a bit of spotting and bad stomach cramps (feel like period pains) I was ment to come on my period yesturday but I haven't... I took a cheap pregnancy test yesturday and it said negative but I'm still unsure what would you advise