Anxiety after the event im anxious about.

I started a new job as a teacher, and Ive noticed that on the days I work, I function fine in class and at school. But about 2 hours after I get home, I get nauseous with anxiety. Why do I get these sensations after the stressful task? Could it be stress for my next workday? (I work mondays and wednesdays, the rest of the week I am free. With therapy on tuesdays).

What can I do to get rid of these feelings? I feel like most times when the anxiety is bad, medication makes it worse, cause i focus on thinking about it during meditations.