Wished Away (слэш)

Over the last three weeks, Tony has been losing his memories, his mind, and his very core sense of self... and everyone except for him seems to notice.
Tony has forgotten his relationship with Steve and Bucky and can't understand why Captain America and the former Winter Soldier stare at him so sadly. He's become an upstanding member of the Stark Industries board and doesn't understand why that makes Pepper so upset. His lab sits unused, coffee drank in reasonably amounts and he gets a solid eight hours of sleep every day and doesn't understand why all of that freaks Rhodey out.
Tony might be sick, he might be cursed, it could be physical trauma and unresolved PTSD manifesting mentally... or it might have to do with the artifact Tony took from an abandoned Hydra storage facility, the artifact that Dr. Strange discovers will grant the owner a single, life altering wish.
...what exactly did Tony wish for, and what exactly is it going to cost?