Help my calendar wont log my period

I started my period on Monday, a few days early. Every time I go into my calendar to edit the change it pushes my period back another two days. I keep trying to go in an push the button that says my period started today and it just keeps getting pushed back. I also have tried to just move the dates around manually and it just tells me that I cannot add a period so close to another cycle. Has anyone else had this problem, or know how to fix it?