'Jane' Testifies to Nipple Infections, Frequent UTIs During Diddy Relationship

Diddy's ex-girlfriend is testifying about the pain she says she went through during her relationship with the mogul ... saying she had to fight off multiple infections and other ailments.

"Jane" -- the pseudonym one of Diddy's exes is using on the stand -- has run the court through the many freak-offs she says she participated in ... telling the jury she kept doing them because she loved Diddy and wanted to make him happy.

Jane even says she got a nipple piercing for Diddy because she says he told her it would turn him on if she did.

Jane says she went through with the piercings ... but, she explains they ultimately got caught on her lingerie, causing her to bleed and her nipples to become infected.

She testifies that she took them out after about a year ... and, when Diddy saw them, she says he told her he never wanted to see her without them in again.

Jane has also testified that her pelvic area was sore after each "hotel night" -- Jane and Diddy's term for a freak-off -- that she participated in. She also said her back hurt because of the sexual positions she would have to contort into for hours.

Jane says she got constant urinary tract infections while dating Diddy, which required antibiotics. However, Jane says she only told Diddy about her pain sometimes ... while other times she would bear the pain and endure another freak-off. She says she took ecstasy for sexual energy and to numb the incredibly intense experiences.