Being over dosed can cause problems. And, there can be interactions with other meds. Is he on any other meds for something like depression or anxiety?
I feel for you. There is practically nothing worse then the unknown and that is basically what you are dealing with. One thing to keep in mind -depending on the dose - the medication is out of your system in about 4 hours for IR and about 8 hours for the extended release. Thus, at night (if he takes his meds in the morning) he should be back to his old self.
Hope this helps.