It’s probably time to look at a combination of meds so he can take a stimulant and get the benefit of it. As brandi said above, guanfacine or Intuniv is often combined with stimulants to help with rebound and moodiness.
Many kids take a low dose afternoon booster as well, so that the medication diminishes more slowly.
There are two types of stimulants: amphetamine (Adderall, Vyvanse, Evekeo…) and methylphenidate (Ritalin, Concerta, Quillivant…). Almost everyone does well on one type or the other, but not both. It sounds like a methylphenidate might be better for him since he had no negative side effects, IF you can get a med and dose that work for your son.
Sometimes using a liquid is helpful because you can tailor it to any dose, where the pills only come in certain increments with big gaps.
ADDitude Community Moderator, Parenting ADHD Coach, Podcaster & Author, Mom to teen w/ ADHD, LDs, and autism