Is this breakthrough bleeding????????

i am on the pills and my first month i had a period with my inactive pills,and this month i took them and my period was three or four days late .now i just came on today(friday).i took a home test last week it said negative or i will be getting a blood test.could this be pregnancy? i am also having bad cramps and been very sick today,and i really couldnt eat and was very shaky today