I'm obsessed with finding my childhood best friend
That sounds interesting, what makes you want to find him.
He was my best friend. I miss him very much, he always comes to my mind whenever I try to sleep
I'm happy you're trying to rekindle old friendships.  Reconnecting with a childhood friend can be very pleasant!  I hope you find him so you can stop obsessing over it so much.
You don't understand. I've been tirelessly looking for him. I've tried everything.
Give it time, you will find him if it's meant to be. Things like this can take awhile.