Thank you for your query.
I can understand your dilemma at your cousin's health. It is very difficult to say why Eglonyl was prescribed to your cousin till all the prescriptions and investigations are reviewed. It is advisable to discuss with the doctor who has prescribed the medicine.
One needs to find why and how has mercury reached the CNS? Could it be that he was prescribed some ayurvedic or local treatment by someone?
As a number of doctors and specialists have been consulted I would suggest that a primary pediatrician
should play a team leader's role and consult the relevant specialist and guide you for the further course of management so that the child's faculties can be best utilized for his overall development.
I hope I have answered your query to your satisfaction.