I have no experience with this, but I would suggest speaking to your GP to get advice.

I think a 7yr old is still very young to recognise and verbalise feelings. That is something you can help your child with and then offer positive alternatives to express those feelings like jumping on the trampoline, sensory toys / sensory gym, dance, drama, sports, karate / Martial arts or painting.
I the meantime when it happens I think it’s important you control your own emotions and stay calm, name and describe what you see and describe what you would like to see differently and help him canalize his feelings.
I would talk with his teacher as well and ask if he shows his behaviour at school as well and rule out speech, dyslexia or any other delays.
When he continues to struggle I would certainly go to the GP to get a referral for a child psychologist

My daughter had similar behaviours and i was at my wits end as what to do. Eventually we found out she had expressive language delay so this led to her frustration and behaviours that hurt herself or me and her siblings. There was no easy answer but one thing you might want to look into (aside from medical/physical delays) are sensory aids. Things like a silicone necklace helped my girl – she learnt to bite that instead of herself or others. Its non toxic, safe and gave her an outlet and us the time to work through her frustrations. Many other things are available like hand held sensory toys, an area thats safe where your child can physically get out their frustration….just a different perspective that worked for us. Good luck!

Have a good talk to him and maybe even take him to a dr or psychologist. He sounds like he is struggling to express his feelings.

mom56312 has given you some great advice. Your child could have a form of Autism (a friend of mine was a Nanny to a child with the same actions) or ADHD which a family member has. I would definitely follow up on the suggestions given. Does your child have any medical condtions that could be associated with it. e.g. could he be having seizures in his sleep and that be the after effects. Does he stare at things and ignore you when you speak to him? It could be absence seizures. Does he display the same behaviour at school at all? It may be worth talking to his teacher and check his learning standard. He may be behind in something and be frustrated about that too? Could he be being bullied at school?

Can your child express himeself and feel like he is been heard? My son was a selective mute until he was 5 and a half and use to slam him head into the ground a lot or hit the walls. He then got some pshyclogical help and speech theropy and has came along in leap and bounds. He even the other day walked up to his sister and said you really hurt my feelings before. Once upon a time he would of bitten her. My son biggest issues was not knowing how to express himself outloud to others, or when he was trying and couldnt get the words out people were telling him off for been worked up which would just make him that much worse..