Brandi Glanville didn't get any sexual healing from her last dude ... more like a sexual itching -- because she thinks he gave her ringworm with his you-know-what.

The reality star spoke with prolific former pornstar Lisa Ann on the most recent episode of her podcast "Brandi Glanville Unfiltered with James Maas" ... and she asked Lisa if she knew anything about "sexually transmitted ringworm."

Lisa says it's a huge problem in the industry because it's so contagious ... and asks how Brandi thinks she got it.

BG says she dated a dude in the adult film world ... and Brandi now thinks she has it in her throat ... we'll let you do the math on that one.

From there Brandi dishes on all the dirty details ... watch the clip for yourself to hear all about it.

Brandi's dealt with a few different health issues over the years ... including silicone from ruptured breast implants leaking into her lymph nodes which caused a facial disfigurement.

Anyhoo ... you might want to get yourself checked out BG -- sexually transmitted ringworm is an itch only a doctor can scratch!