Hi. Thanks for your query. Read and understood the history related to your grandson, namely- ADHD, epilepsy and autistic. HE is on Epilum, Kepra, Lamictal, and Ritulan. He has no muscle tone and an extremely fast metabolism. The cause of your concern is foul smell coming from the nose. The commonest cause in such patients is the atrophic rhinitis. This is the condition in which there is saprophytic infection causing the typical smell. I would advise the following in such a case. Consult an ENT Surgeon for clinical evaluation, examination. The boy needs nasal cleaning with sodabicard solution. Since the boy can not do it, the family members have to learn it. He shall be given a course of an antibiotic, and supportive medicines. I hope this answer helps you.