I would just say that the meds can do weird things that can look like restless leg, tics, etc. Each person can often be sensitive to meds different than another.

So all you have done is great. You cna ask to have him put on a different med to try and see.

I would also ask do you know what may be the cause of the seizures?
I would like to suggest given he has seizure sometimes and other times not. To keep a journal of daily food he eats, stresses that might cause them(tics or seizures)

I have had seizure for 38plus years and still keep a journal as it helps me to see what I need to avoid orchnage to help me avoid seizures.

Things like diet(wheat, sugar etc) stress, anxiety, lights flashing or fatigue etc. can all be triggers that can cause seizure to come on. The more one learns what might have led to it will help you to help him avoid it.

I know this is a very hard time for you and your family. Know we are here to be of support. Also, love, gentleness, encouragement and compassion for all of you is important!

Best to you and keep us posted.
Blessings!