THONNIR Follows Me EVERYWHERE!

[bigbadbil]

Hi all. Been playing the latest version of Skyrim on PS4 for about 2 months and am MAJORLY addicted.
I now have a problem that I don't know how to solve. While in Morthal, went with Thonnir to the cave to kill the Master Vampire. Had no merc/companion because my dog had just ben killed. While in the midst of battle I accidentally lit Thonnir on fire. After that, he went berserk. Started hacking on me and running around in bonkers mode. I could not kill the Vampire while also being attacked by Thonnir. Exited the cave with Thonnir right behind me hacking at me with an axe.
I though I might lose him when I left Morthal. He did calm down but stuck with me EVERYWHERE I went... and still does even though that was 2 days ago. I have since hired a replacement merc which the game allowed so I guess it doesn't consider Thonnir my +1.
How do I get rid of him? I am a thief and an assassin. When I steal something, he says "Stop thief!" and here come the guards.
I really hope someone out there can help me. His repeated dialogue and constant bumping into me is really ruining the experience for me.
Thanks in advance.
Bil

[Wolfborn]

From the notes on Thonnir's wiki page:

If you attack him (or accidentally strike him in combat) he will not accept a yield, and will continue to target you. As he is an essential NPC, this can make combat situations very precarious. If you do strike him, whether by accident or on purpose, the only way to prevent him from fighting you is to load a previous save, or by entering stopcombat command to Thonnir in console.

Looks like your only hope is to reload a save from before you went to Morthal.