Candida /yeast or fungi infections or overgrowths are real-- common areas that can be tested for as well as seen are in the mouth, under nails (toe and finger) and vagina.
It is only logical that intestinal bacteria can get out of control with many meds as well as diets -- almost all antibiotics warn that it can occur but since candida is a normal part of your system --no test has been developed so far but there are many symptoms to make a diagnosis and it is often mis DX.

The prescription drugs that are commonly used are to treat yeast infections are Nystatin & Mycostatin, Diflucan, Sporanox and others.

OTC remedies are Kolorex, caprylic acid, Pau d'arco, wild oregano oil, Olive leaf extract, and garlic.

To re-establish the friendly bacteria in your GI tract--- you need to eat yogurt or Kefir and take a good probiotic supplement twice daily.
Yeast thrives on sugar so your diet should be not contain any sugary food-- an anti candida diet is best since it starves the candida/ yeast back to a balanced condition..

I wish you well ---Harry