Wendy, there are a number of drug interaction checkers online.
Here's one of them
http://reference.medscape.com/drug-interactionchecker

I have to tell you though aside from everything else, my son was on a very low dose of Clonidine when he was quite young. It made him very sleepy during the day despite the dose being very low and despite it being given at night before bed. If the daytime tiredness is a new thing since the Clonidine was added, then perhaps the Clonidine dose or time of dose needs adjusting. Just a thought. Clonidine made my son very different. It wasn't good. [p.s. It's really important never to discontinue Clonidine without a taper]

Here's the link to the NeuroTalk Epilepsy Forum here in case you want to ask the users over there. They may be able to help in some way.

Also, from my limited understanding of seizures, a normal EEG doesn't necessarily mean that no seizures are occurring.

Don't forget there is also PubMed where you can search any specific keywords for information.

This article is quite old but there is a lot of information in it and there are a lot of references at the end which might be helpful.
The British Journal of Psychiatry (2000) 176: 357-362
Catatonia in autistic spectrum disorders
Wing and Shah 2000
http://bjp.rcpsych.org/content/176/4/357.long

"Most frequent manifestations of catatonia"
from Wing and Shah, 2000
http://bjp.rcpsych.org/content/176/4...expansion.html

Autism Speaks.
Does Our Teen Have Autism-related Catatonia?
http://www.autismspeaks.org/blog/201...ated-catatonia
Dr R Robinson
Jan 3, 2014

Edited to add:

I just had a thought and so am posting a small snippet from a book regarding
'Tic Mimickers' [Starts off with Dystonia vs Dystonic Tics and more...]
Tourette Syndrome, Volume 99
edited by John T. Walkup, Jonathan W. Mink, Peter James Hollenbeck
It's not new either, but has a good description.