Background: Pediatric acute-onset neuropsychiatric syndrome (PANS) is a symptom-based and clinically heterogeneous condition characterized by an abrupt and dramatic onset of symptoms such as loss of motoric and cognitive abilities, anxiety, compulsion, tics, and eating disorders. PANS is a new diagnosis and the condition has gathered controversy in research and clinical practice. Aim: We aimed to investigate the process by which parents of children with PANS acquire knowledge about the condition; the causes that lead parents to search for knowledge; the ways in which they search for knowledge; and the manner in which this knowledge is received by medical care professionals. Method: The study employed in-depth semi-structured, individual interviews with 13 parents of children diagnosed with PANS. An inductive qualitative thematic analysis was used as a guide for analyzing the data. Results: Challenges to understand their child’s illness and receive effective care led the parents to search for knowledge about PANS and provide an explanation for their child’s symptoms. They used personal and social resources to search for knowledge. They felt trusted and encouraged when clinicians endorsed their knowledge. On the other hand, when they were dismissed as a source of knowledge, they experienced a lack of trust towards professionals. Conclusions: A driving force for parents’ search for knowledge is a perceived incapacity to give meaning to their experiences. Another reason is mistrust of healthcare staff’s existing knowledge.