Why do they do this?

A couple of years ago I transferred from private, Catholic school to the local public school. I just needed a better education than was offered at the private school. I haven't made ANY good friends since the switch and I really want to stop just hanging out with my parents on the weekends. The friends I had, ones i had grown up with and gone to school with since preschool, started ignoring me as soon as i transferred. It was like I was some kind of alien. They have not talked to me much since the transfer. The schools were only a block away so distance was not the matter. I haven't tried to ignore them. But I really want to know what made us grow apart? Could it have been something I did? Please don't tell me to 'buck up and ask them', they just ignore me. But i really want my friends back.