Is there any self test to know fungal infection in mouth especially in tongue?can it be a cause of halitosis?

Candidiasis-thrush: A doctor or dentist (and sometimes pharmacist) can tell you if you have the yeast infection candidiasis, which can cause halitosis. The mouth usually has red spots or a white area that when wiped off leaves a red spot. It is usually treated with nystatin. It is important to find out the cause of thrush as it can sometimes be a symptom of another disease.

Diagnosis: Usually a visual inspection can tell if you have thrush (fungal) infection intra-orally. For definitive diagnosis you should go to your doctor.