Should I tell my dad I'm on my period?

He is a doctor(surgeon). My parents are divorced and I'm with him all summer. I only have my dad and my older brother. I am 13 and this is my first time getting it but my mom already told me everything because 13 is pretty late so she wanted me to be prepared. I don't want to tell him cuz it would be REALLY embarrassing but I am using the 3 pads in the kit my mom bought(so embarrassing)and I need more. My brother is mature(he is 19) and wouldn't make fun of me but i think that would be worse.Would my dad know since he is a doctor and all??? HELP!!?!?!?!???!???