I'm not a doctor so I don't know how much help I can be. It sounds like your symptons are similar to early
pregnancy symptoms that many women experience. If you had a negative pregnancy test I would guess that you are most likely not pregnant especially since you did have a period the next week. However if it is early in the pregnancy the levels of the HCG hormone which trigger a positive pregnancy test may be in too small levels to trigger a positive response. If you are really worried you could buy another test now. If you decide to wait and your next period isn't normal you might want to check with your doctor to determine whether you are pregnant and if everything is normal.