Nexplanon

Sooo this is probably commonly asked but i am lost and scared right now. This up coming weekend is very important, and i would not like to be on my period bleeding everywhere. But I was wondering how do you know if you are on your period or not while on nexplanon? Because well i’ve been cramping like non stop since last Saturday i believe and i have been fatigued and very very sensitive and emotional... Please help ASAP!