Megan Thee Stallion was Treated for 'Gunshot Injury' at Hospital

Megan Thee Stallion's injuries to her feet, after Tory Lanez allegedly shot her, were so bad she had to go into the operating room ... TMZ has learned.

Sources connected to the investigation tell TMZ ... the rapper's hospital records show she was treated for a "gunshot injury" when she was admitted to L.A.'s Cedars-Sinai Hospital. That was shortly after police pulled over Tory's chauffeur-driven SUV around 4:30 AM on July 12.

We're told, Megan told doctors she was barefoot when she heard a loud noise and immediately felt pain in both feet, and said she initially thought it was from stepping on glass.

Instead, our sources say Meg underwent a surgical procedure to remove bullets, or bullet fragments, from her feet.

As we've told you ... Megan says the incident has left her "hurt and traumatized," and the LAPD is still investigating Lanez for assault with a deadly weapon, but so far, he has not been charged.

As we reported, video of the ordeal showed cops pulling over the SUV -- with Lanez lying face-down on the street and Megan tip-toeing gingerly ... leaving bloody footprints with each step.

Our sources say Tory allegedly shot Megan in the feet as she exited the SUV, on the heels of an argument that erupted in the SUV. He was arrested and booked for possession of a concealed weapon ... the handgun cops found in the vehicle.