Try to keep them busy doing activities even if they don't want to, try not to let them focus on it.
Keep them as far away from social media as possible, nothing good can come from that.
Maybe do some family game time? When mine went through the same thing we spent a whole Sunday playing games as a family. I had to bribe him to play (a night at the movies with a few friends, which would kill 2 birds with 1 stone, keeping him distracted).
He played... begrudgingly at first, but he played.
We let him pick all of the games (which his siblings weren't too happy about (which was more entertainment for him) & they soundso understood that he was going through a tough time.
Before he knew it, he was smiling, laughing & having fun again.
We also invited a few buddies over towards the end to take over the reigns from us & play Fortnite (an INCREDIBLE distraction!).
No, it didn't rid him of all of his suffering, but it showed him that there were still good times to be had, which helped a great deal.
Hugs to you, OP.