I don't think it's uncommon. No matter how well trained, I think teachers get frustrated with students from time to time.
I personally don't mind medication questions most of the time. It helps me determine when a medication re-evaluation may need to be done. But it can get frustrating when I feel pressured for a quick fix, because there aren't any.
The fact is that some kids with-ADHD do not respond to ADHD medications.
If you're comfortable with your son's diagnosis and the psychiatrist's medication management, all I can recommend is that you reiterate the same info to the Sp Ed teacher. If you're not, you may need a new multidisciplinary evaluation (private and through the school district) and a new child and adolescent psychiatrist to manage medication.
Hi 3butterfly, and welcome to the site.