Sleep issues

Why is my son having so many issues with sleeping lately?? He was sleeping through the night for 6.5 months, then he just quit. After trying everything for 2 months we got him back to sleeping through the night again in his bed. Now he can’t stay asleep for 3 hours! He is up by 12am sometimes 2:30 but he is so restless after that. He flops around, sits up, crawls in the bed, he will not settle down and stay asleep.

I don’t know what to do anymore but I’m losing my sanity.