pregnancy test didn't work.

My period started a couple days ago, and the morning of the first day I threw up after severe nausea. I've been also having lower back pain and some cold/hot flashes. I bought a pregnancy test and drank a lot of fluids before peeing. The test showed no results and I'm a bit frustrated. I only have one and I don't want to have to go out and get another. This test was also like $12. Puking like that isn't normal when I'm not even sick. I didn't eat anything bad. Could I be pregnant?