I get these unexplained chills episodes quite a bit. A hot Epsom salt bath helps and taking ginger capsules. Ginger warms you like nothing else. One time I was so cold my teeth were chattering, I took three capsules. A half hour later I was a little better, so I took three more. Take three capsules at the first sign of chills and three more every half hour until they subside. I have taken a lot of notes from this thread and plan so see a doctor now that I can afford insurance. If I find anything I will let you know.
It sounds like he is having seizures. One of the type of seizures that I have, gives me some of the same symptoms. If he has not had a EEG or a Cat Scan he needs it.
It looks like the cns is affected. I would ask in the neurology group. Has he got an EEG, MRI tests?