Period date may alter up to 7 days and it is considered as normal thing. It occurs mostly due to hormonal
imbalance & mental stress
Here, you need to undergo one blood test
for beta-hcg & TVS scan to rule out conception at the earliest.
Following test report, you can consult with your gynecologist for next line management. In exclusion of pregnancy
, other relevant investigation may be required.
All the best.