The problem is more complicated than it sounds. The official treatment protocol for PANDAS is to perform a throat culture for strep and then treat with antibiotics if the result is positive. (Source: https://www.nimh.nih.gov/health/publications/pandas ). In other words, it's the same as normal treatment protocols for strep.

The idea of PANDAS from occult (aka hidden, not producing positive test results) strep infections is less proven and considered rare, although it is mentioned in official treatment recommendations such as those above.

The problem providers face is that some parents will read about PANDAS on the internet and assume it is the explanation for their child's problems, despite having negative throat culture. They jump from doctor to doctor demanding antibiotic treatment despite the negative test results, guided largely by their internet research. It's not hard to find PANDAS parent groups on Facebook or Reddit where someone can post vague symptoms and a chorus of group members will response "sounds like PANDAS".

The difficult part is that for some of these patients, PANDAS might be the right diagnosis. However, once a diagnosis becomes a cult favorite on the internet doctors get inundated with parents demanding antibiotics because their Facebook groups told them that's what their child needs.