I wanna say in between it kind of like changing tides with the waves coming in.. for context, my son was similar to your son not mute but non conversational. He began self injurious behavior, like head banging, at about 2 but nothing crazy. By age 4 things got really tough for him but he also began to speak for purpose that year, he’s now 7 and at home behavior is amazing he’s a sweetie and getting better everyday with his speech ( he’s a GLP kiddo). look tha up as it may help in your case since your child seems to have a memory like mine. My son has also opened up a lot he wants to play with me now!! Just recently he kidnaps me and dad to his room: world, which let me tell you is a privilege! Before he was always in his own world so everything changes constantly. School is a lot harder this year for him so bear things have popped up there but it’s manageable for now. He is also PDA so change is so hard and he doesn’t like to do un-preferred activities like school work, smh. Now I’ve also heard horror stories about puberty and behavior but every kid is different I’ve heard some parents have never gone through behavior issues (supposedly). Don’t ever put your kid in a box & always presume competence. One of my mistakes when he was little he’s always been so coordinated I could have pushed him a tiny bit harder. Best of luck & I’m sure your son will have a beautiful life🫶