Don't want to eat anything?

About 5 days ago I felt constantly sick and didn't eat much just drank loads. This sickness went away two days ago but now I just don't feel anything, I don't want to eat. Its not that food makes me feel ill, I just have no desire to eat and it is a lot of effort to force myself to eat. I don't know what caused the sickness but I was never actually sick. What's wrong??