Hi there,
It really depends on your normal cycle and flow of your periods. If your
menstruation does tend to go in 26-28 day cycles, and the amount of blood flow seems normal, then it is quite likely that you are experiencing normal menstruation. The symptoms might have been just due to a stomach bug.
However, if you feel that the blood flow is unusually light, or the bleeding did not come at your normal time, then I would be more cautious and repeat the urine
pregnancy test again after a week. It might be too early on to show on a urine pregnancy test. If you want it confirmed earlier, you local doctor's will be able to perform a beta-
hCG blood test, which is more accurate at this stage.
If you are bleeding very heavily with clots, or have intense lower stomach pains, get help. This is because you might have gotten pregnant and are now experiencing a
miscarriage.
Hope this helps, and all the best to you.
Regards,
Dr. Teh