Jodi Arias -- I Got Hepatitis C in Jail ... Now I'm Going After Sheriff Joe Arpaio AND Nancy Grace

Jodi Arias got more than a murder conviction in Arizona ... she got Hepatitis C ... and she blames it on Sheriff Joe Arpaio, who she also claims is in a conspiracy with none other than Nancy Grace.

Jodi -- who was convicted last year of murdering her ex-BF Travis Alexander, is awaiting the death penalty phase of the case.

Jodi claims in new legal docs -- obtained by TMZ -- while she was in the custody of Sheriff Joe ... she was given a Tuberculosis shot with an infected needle, which gave her Hep C.

She also claims her left silicone breast implant leaked and caused a fungal growth. Jodi alleges she was denied medical care.

Jodi also claims Joe has put cameras in her cell and forces her to say the Pledge of Allegiance every morning or else she won't get fed.

Now Nancy Grace ... Jodi alleges Joe intercepted sexual letters between her and Travis' cousin and leaked them to Nancy, who then blabbed about them on TV. Nancy claimed the 2 were getting hitched.