Please help! I'm not sure what to do...?

My friend has never been very athletic, but she's gotten WAY better in the past few years. She has actually wanted to run. She joined cross country and was having a hard time. But it wasn't because she wasn't in shape. Her legs were hurting her to the point of tears. It would start in the front then go to the back then down into her foot. She's very stubborn and wouldn't go to the doctor. I went to cross country with her last week (I'm really busy and don't get there too often) and I ran with her. we came in half an hour behind the person in front of us. Needless to say we were last. I got her to go to the doctor and the doctor gave her a note saying that she couldn't run for two weeks. She sulked and pouted, she REALLY wanted to run. She sent me an e-mail today saying that she was going BACK to the doctor's office and she would call me and tell me everything when she found out what was up. I responded saying that my cell phone was dead so she could call my house phone or e-mail me again. Later I checked my e-mail and she had responded. She told me not to call her and that she wanted to talk to me in person because it was a long story and she would need a shoulder to cry on. She kept telling me not to call over and over again. She told me that she would talk to me at school first thing in the morning and that she wanted to be COMPLETELY alone when she told me. I don't know what to do. I'm so worried about her. I'm supporting her, and being here for her but...What else can I do?! I feel useless and I'm confused about why she won't tell me. Please be serious and help me! Does anyone know what could be wrong with her? I think it may be more serious than Shin splints!