2 year old won't sleep

My 2 year old won’t sleep, he’s up every hour on the clock, screaming, flailing, kicking, absolutely inconsolable… I requested his paediatrician send him for a sleep study to get told “this is normal for toddlers” … I will be taking him to a different doctor tomorrow for a second opinion, but I’m at a loss. He wakes up my other 3 children all night long because of the screaming and crying. Anyone have any suggestions or been through something similar? I guess I’m just looking for ideas to help and some validation that I’m not crazy that there could be something medically wrong with my baby.
Signed one heart broken mama