"Morning Spike" anxiety?

We started our 5.5 year old on 10mg Metadate CD. The initial week was good. No negative side effects but also didn't seem to have much impact to the ADHD symptoms. We went up to 20mg. Initially was great. But the last 2 weeks he seems to have anxiety during the initial rise of medication. As it wears off the anxiety goes away and he doesn't even seem to have the "crash" people talk about. I have an appointment with his developmental pediatrician tomorrow for a med check but just wondering others experiences.

I'm thinking either the 20mg is too high of a dose or maybe we need to try a different version of Methylphenidate?