Quoting Mariah Bailey:" he talks but 100 percent clear when he was younger he use to slam his head alot and scream 24/7 if he ... [snip!] ... to have to sneak out so he wouldnt throw a fit and sneak in cuz as soon as he would see me he would flip for me to pick him up"
It sounds like he is having trouble vocalizing his frustrations. You need to press the issue of using words. Give him a voice.
When he starts yelling CALMLY tell him to use his words. Just keep telling him OVER AND OVER AND OVER again. Explain to him that screaming is not helpful he needs to use his words.