Hello and welcome to Healthcare Magic. Thanks for your query.
It is impossible to know the exact identity of a medication without knowing its generic or brand name or any other significant details about it. There are several different medications given for migraine
and are a lot of different anti-histamine
The only possible chance would be to trace his old medical records (many countries have a computerized database) or find his old prescriptions. Alternatively, you can take him to a doctor for a fresh evaluation of his problems, so that appropriate medication can be prescribed.
Wish you all the best.
Dr. Sheeba Stephen
Emergency Medicine Specialist