Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
Call emergency services if someone has trouble breathing, becomes unconscious, has a seizure, may have been poisoned, has a serious unexplained injury, or appears to be in immediate danger.
If you suspect a child or dependent adult is being made ill but there is no immediate emergency, contact an appropriate child-protection or adult-safeguarding service.
You can also tell a healthcare professional, social worker, teacher, or police service.
Describe specific events, statements, or records rather than trying to assign a diagnosis.
Seek routine medical follow-up when there are concerns about unnecessary medicines, conflicting diagnoses, repeated unexplained symptoms, or care spread across many services.
A coordinated review can check what treatment is still needed while safeguarding concerns are assessed.
The article also says
Avoid confronting the suspected person if doing so could increase danger, lead to evidence being destroyed, or cause the affected person to be removed from care.
Every sign above is quoted from the sofidex article on Factitious disorder by proxy. If you are not sure, err upward — it is always reasonable to be checked.