Question about fertility appt

I met with a fertility specialist last month and he just did a pap and got some history and said to come back this month on my 3rd and 14th days of my cycle. We talked about so much at the appointment (& I was nervous & emotional & trying to keep it together) & I don't even know why I'm going in on those days of my cycle... Anyone have any experience with this or a guess? I feel like an idiot calling to ask.