Weird Period

So a little background... For the past few months my periods have been coming early.. I've either had spotting three to four days early or my period came full on three or four days early.. I normally have pms symptoms a week to a week and a half before.. This month my period came a day late and it was kinda weird.. I normally have tiny clots in my period.. And this month there were none.. I didn't have any pms symptoms beforehand.. The blood looked kind of watery.. I had no cramps.. Any ideas as to what this could be??