Hi there ~
You classically describe the symptoms of a disorder that is very similar to the one that I have had experience in seeing in my daily practice that is bipolar disorder
. I hope this helps if I suggest that you see a psychiatrist
to find out how best to help your brother. I am unsure of your locations but would look for local resources to be able to reach out and help your brother.
I hope this helped. Take care and have a lovely day!