Focalin is little different than just methylphenidate — it has some dex added to it. It could be that he doesn’t do well with that added component. Or it could be that the dose it too low for extended release.
With the IR medication, he’s getting the whole dose dumped at once, so there’s a big change and then a big crash. With ER meds, the dose it time-released.
Definitely talk with the prescribing doctor for adjustment.
ADDitude Community Moderator, Parenting ADHD Trainer & Author, Mom to teen w/ ADHD, LDs, and autism