Preface: Sonic asked me to post this for him because he did not have a forum account. I checked with Kovos and he said it was fine.
Okay, so Sonicboom29 told me a story on how Catty610 stole a wither skull from him.
He basically said he threw a potion at Catty in his [his is assumed to be Catty's] shop so Catty retaliated by killing Sonic with lava. When Sonic died, apparently Catty stole his wither skull and now, although Sonic has offered a diamond in exchange for the wither skull he stole, Catty will not give it back.
All Sonic wants is the skull back. Again, he even offered a diamond in exchange.
I don't know date or location of this incident because Sonic signed off before I could get the information, but Kovos told me to make this report anyway.