am i pregnant

so the last week i threw up bright yellow & had loose stool... only twice my stool was yellow & ever since then i've been having headaches & small stomach pain in the middle of my stomach. i didn't feel like throwing up or like i had diarrhea at first, like it was just pain everyday. but yesterday it got worse i have a fever now & headache & nausea, my whole stomach hurts now. i got off my period jan 1, it was super heavy.. i had sex twice last week using the withdrawal method.. could i be pregnant?