I Am A First Grade Teacher. I Have Been Very

I am a first grade teacher. I have been very tired for several weeks. I come home from work and lay down and sleep because I'm exhausted. at night I just sit . I am having a hard time focusing and staying alert. Now Ive noticed I am having heart palpitations and some shortness of breath when I lift things or move around. I had a physical at school the other day and my blood pressure and heart rate were good. Also they did a free scan and it showed no blockages in my neck or legs and chest. So I don't believe it is heart related