1 week early period very light on off for 4days at first it was watery and bright red then second day it was brown and watery and then back to red?

Periods can change: It is not unusual to have some mild variations in your cycle. Although these minor variations are rarely early signs of a more serious problem they usually return to normal over time. In many cases hormonal birth control will help to regulate your cycle. See you doctor if these persist or worsen.

No way to tell: Menstrual irregularities are very common and can be due to multiple factors. Would not become concerned unless this continues unabated or becomes progressively worse. Without knowing your entire history and examining you it is impossible to go any further.