I can completely sympathize! My 3rd grade daughter has struggled with reading since kindergarten. Although I swore I’d never give my children stimulants, her pediatrician recommended at least trying. We worked thru a few different medications until settling on Adderall extended release, which is fast acting but doesn’t last much past the afternoon so there are no sleep troubles.. Since starting a year ago, she has made tremendous improvements, although is still behind. It’s very much trial-and-error with the medications, but keep at it until you find something that he responds well to. The biggest thing to remember (for both you and him) is that any medication he tries should never change the way he FEELS, nor should it change his personality. If it does, the dosage is likely too high!
Another option for you is to explore what’s called a 504 plan. It is simply a bit of reinforcement to ensure that he’s understanding the material and perhaps accommodations to complete testing, etc, with a bit of extra time. Sometimes, a little extra time is all it takes! Understood.org has a lot of fabulous information! https://www.understood.org/en/school-learning/special-services/504-plan/the-difference-between-ieps-and-504-plans