I thought we had a thing but now she has started avoiding me

She always used to text me and talk to me every day and I could really tell she liked me. She had this nickname that she called me called "bus buddy" even though we don't o on the same bus but she went on the same bus as me for about 2 days. She always used to walk past me when I'm hanging out with my friends. During the weekend I texted her to see if she wanted to go to the snow with me and my friends but she said she was already going away for the holidays so she told me to ask her best friend if she wanted to go because her friend has never been to the snow so I asked her friend and she said she was going to her grandparents for the weekend which is when we go to the snow. So at the end of the weekend I texted her to ask where she was going in the holidays just to start a conversation and she never replied. So after the weekend I came back to school and ever since she had been avoiding me, ignoring my texts, ignoring my facebook messages and not even saying hi to me at school anymore. Please help! I love her so much. I've never loved someone so much in my life. Now I go to school feeling depressed everyday and crying every day. Does anyone have any idea why she is doing this? And what can I do?