Is it ok to write him an email after he has ignored me for so long?

I have been seeing a guy in medical school over two months now. About a month ago, he asked me to be his girlfriend. The week before last week he had midterm exams so I didn't hear from him at all. That weekend however, he had asked me out previously and canceled the plans, it was my birthday that weekend and Valentine's day on Monday. All weekend he only texted me then we chatted online on Monday. He said he was sorry but that he was busy studying. When I asked him about his plans for Spring Break he said he would be busy studying. He hasn't made any future plans with me. I have not heard from him in a week. I texted him yesterday after 6 days asking how his weekend went and he ignored me. Previous to him, I only had one boyfriend who became my fiance, and he died this past October of murder. He knows this. I feel like e-mailing him, asking what the hell happened and if I did anything wrong to know for the future, but I'm pretty sure this will make me come off as psycho and or clingy. Should I just sum this up to a bad experience?