69's baby mama, Sara Molina, had gone through a bout of depression from being holed up at her house during the pandemic ... according to her manager. So, she went down to Colombia for a little pick-me-up in the form of a Brazilian butt lift and a 360 liposuction.

Thing is ... after Dr. Humberto Peña performed the 5-hour surgeries over the weekend, Sara, who has Multiple sclerosis, had a severe MS flare-up hours after the surgery ... her entire body was racked with pain.

We're told Sara was given nausea medicine but doctors also removed a pain pump that had been placed under the skin of her abdomen to funnel medication directly to the source of the pain. We're told this helped, but she still has big issues. She can't even lie flat.

Sara now rests in a special recliner and although she's still experiencing pain ... we're told she's recovering at the posh Lluxe Recovery facility in Colombia until mid-May.