Any advice/experience with 4yo taking ADHD medication?

So my son has always had some challenging behaviors, though they were always for the most part within the realm of 'age appropriate'. Looking back I think we recognized the hyperactivity by about 2 years old.

He just turned 4 and once school started it was like a switch flipped. All the trademarks of adhd but he was hitting so frequently and severely (kids and adults) that the school couldn't handle him and we went down to 2 hours a day. He has torn apart classrooms. They are better managing him now, but he spends almost no time in the classroom or he will have outbursts and destroy things or hit and they have to evacuate his class.

We asked his doctor to refer us to a pediatric behavioral specialist and she immediately diagnosed him with adhd. And suggested starting medication right away. I know this is unusual for his age and I was hesitant but we ended up trialing 3 seperate medications, none of them more than a day or two as the side affects were l awful. On one medication he didn't sleep till 4 am. Another he became so incredibly angry and aggressive, another he was so emotional and had awful mood swings and none had much affect on the impulsiveness though it helped a bit with the hyperactivity.

I am wondering if anyone else has any experience with this? We have decided to take a bit of a break before trying again. I know the first medication was made for ages 6 and up and the pharmacist wouldn't even fill it for us until speaking with the specialist. It makes me a bit nervous.

My son is big for his age and very strong. If it wasn't for the safety risks his behaviours cause I would manage without medication, but he can't even be in the classroom.

Anyone who has gone through this, or has any advice it would be greatly appreciated.