The nausea followed by hallucinations and lip smacking is consistent with a seizure called a complex partial seizure. Occasionally these seizures can develop into grand mals.
The most common cause for seizures in his age group are old strokes (may have been very tiny and not ntoiced before). The second most common group is the idiopathic (we don't know what is causing it) group. Other causes such as tumors, and vascular malformations also need to be evaluated. The MRI will detect most causes for seizures. However, a special epilepsy MRI, like the ones we perform at the Cleveland Clinic, may be better at finding causes.
What I would recommend is that he see an epilepsy specialist at an academic center. They will be able to better evaluate this problem and make recommendations regarding treatment.
I will give you a couple of links that you may find helpful.
http://www.epilepsyfoundation.org/
http://www.neuropat.dote.hu/epilepsy.htm
http://www.epilepsy.com/
This last one is a forum of those diag with E.
http://brain.hastypastry.net/forums/forumdisplay.php?s=&daysprune=&f=133
I hope that helps.