I want to know my ovulation my period comes on 1 of March I apply ela app it says I should start sex…

I want to know my ovulation my period comes on 1 of March I apply ela app it says I should start sex from 12to 19 which I did but since last Thursday I'm feeling weak, faver ,headache very weak but today feels like something is coming out I checked and wipes it looks like pick blood but is not coming out much