Pain as therapy

There was a documentary I saw once - I’ll look for it…it was about bee stings. Had the same effect from what you are describing with the tattooing.

Edited to add:

https://www.medicinenet.com/script/main/art.asp?articlekey=50602

Wow - it’s come a long way… lots of info on the net.

I saw this about 35 years ago…never thought about it till I read your post.