Erik Menendez Undergoes 2 Surgeries for Kidney Stones, Still Needs Another

Erik Menendez has undergone a second "successful" surgery for complications related to his kidney stones ... and is expected to go back under the knife soon -- this, according to his daughter, Talia.

Talia posted the medical update late Wednesday evening on an Instagram account she runs on behalf of her father through marriage, explaining he needed surgery due to his kidneys "having multiple large stones."

Talia -- daughter of Erik and Tammi Menendez -- added Erik is "currently in pain and feeling nauseous, but is recovering" and that the family is under a great deal of stress over the medical scare.

We broke the story -- Erik was removed from prison and hospitalized last Friday due to his kidney stones.

On Tuesday, his and brother Lyle Menendez's lawyer Mark Geragos told us he was going through a "serious medical condition."

Furthermore, sources told us at the time California Governor Gavin Newsom is reviewing Erik's change in medical condition to determine if a "prison furlough" is appropriate. So far, there's been no update on that front.

As we've reported, Erik and Lyle are scheduled for a parole board hearing next month to have their eligibility for release considered after they were resentenced to 50 years to life, making them qualified for parole.