I have a plott hound feist that is days away from being four months old. She has been having chronic diarrhea. She has no loss of appetite and is still her wild self. I have never had dogs before and am concerned. We also adopted a 6 mo black lab from the same rescue and she is fine.

Have the vet check her for hookworms. That sounds like what she has.

Maybe Try Changing Dog Foods.
Look At The Ingredients And Ask A
Veteranarian What They Would Recommend.
The Great Thing Is That She Is Still Playful.
Gud Luck!
May Ur Puppy Feel Better!!