Lithium shouldnt be a big deal

However the Klonopin .. being that its a benzio your body gets use to it and if its stopped suddenly he will go into withdraw. Can be severe Flu-ish symptoms , shaking, stomach cramping nausea diareah and there is the big possibility of seizures.. and that can be a very serious thing. If that were to happen then getting medical attention asap is necessary a certain trip to the ER !

Did he run out of meds earlier due to taking more than prescribed ? if so he needs to have a talk with his Pdoc and explain what happened..

He needs to contact his Pdoc asap.

I hope he is okay