The advce to seek help for your schizophrenia is sound.
If you believe you have sold your soul and are unable to abandon that concept, I suggest you evoke the demon Varnaxis, a human (blood relative of mine) who through many lifetimes acquired power and then, in his final earthly incarnation, actually “sold his soul” as a child.
He is now ascended to demonic status, and will help you renegotiate the terms and attain a more favourable outcome:
Here’s a method of opening sigils to begin contact with him: