Mama June Remains Hospitalized ... Mystery Illness

Mama June is still laying in a Georgia hospital because doctors can't figure out what caused her fainting spells ... TMZ has learned.

According to our sources, Mama June will remain in the hospital an extra night after she was rushed there Wednesday night after she collapsed in her home.

We're told all of her tests have come back normal and doctors are unable to pinpoint exactly what is wrong with her.

Our sources say Mama June did have one theory ... she told doctors she has been extra stressed lately since "Marriage Boot Camp" began airing ... and she and Sugar Bear have been fighting about it constantly.

We're told docs plan on keeping Mama June in the hospital until they figure out what's wrong.