Preggo or paranoid?

Okay; on sunday May 18th me and my friend had unprotected sex.. stupid yes i know; but ive only ever used a condom once.. and im not on the pill or any form on birth control.. He came inside me.. and no ones done that before. I Should have started my cycle Sunday May 24th and i have yet to do so.. ive been experiencing lower back pain and cramps and this disgusting discharge.. and its more than what ive ever had before. ( TMI ) And also this morning i was sick and actually vomited.. but can you even get signs that early or am i just being paranoid? Im going to be purchasing a test to take in a week or so... soo i pray to god im not!!