What do I do to be confident again in running?

I am in high school and I run the 3200, 1600, 800 and 400. At first I could handle it and actually got all 1st places in all of them and even set the school record in the 3200. But yesterday I really had an off day and was struggling to stay with people I could beat easily. Running to me is not all about being fast and winning but it feels like I'm getting to a point where I am lost and confused to how my body is not helping me like it used too. More than anything everyday for 8 months I've worked hard because I want to do well at state. State is in 3 weeks and I am fearing that I won't even qualify for one event. Just that thought makes my stomach churn. What do I do?