Hi, For The Past Few Days I've Had Back Pains,

Hi, for the past few days I've had back pains, feeling a bit sick and nauseous as well as feeling bloated and I googled this and it came up with pregnancy. Being a worried I don't know what to do. I'm on the pill but my cycle ends today (I took my last pill this morning). When I have my withdrawal bleed (if I have it..); can I rule out pregnancy?