Big bro babysitting PERIOD HELP?

Mum + dad away fir the week. 17yr old step bro babysitting. Just gotperiod( not first ) need tampons , med and Im bleeding really heavy. I'm 12 and scared to ask him. How do I ask Him??? Will he be embated will he say no? Help how do I ask/ do I ask. We have a xloshish relationship. Sorri 4 spellin mistakes typed in hurry as scared and need supplies fast abd jst checked all. Upboards non in the house!!!