Hi I Have Been Spotting For About 5 Days Very

Hi I have been spotting for about 5 days very light brown more if I exercise but usually just when I wipe im about a week away from my actually period. What does this mean ? And I also have been having very bad stomach pains that made me feel like having the diarrhea or to vomit. I took a pregnancy test and it was negative but wasn't sure if it was too early as I starting this spotting on sat and will start my actually period this coming Tuesday so I have a week until I should take a test?