Mom says pads cost too much?

Ok so i am 13 and just started my period earlier today. Since my mom is like 53 she does not get her period anymore. So i asked her today if she could run me to the pharmacy to get some pads. She was like.....sorry lindsey they cost too much and then just left. I was like what? I went to her again and was like well what was i supposed to do i am bleeding. She then got all offensive and said do you want me to go bankrupt. I felt really bad then started crying. Later on i searched free tampons and pads on line and got all kinds of free stuff but they wont be here till next period. Wjat happens when they are all gone. Are pads really that expensive. We live it a trailer and we are kinda poor. I dont have any money and need pads. Please help I AM NOT LIEING JUST PLEASE HELP