Big Boss died. I have no idea how.

Explain this one to me, dear readers.

Tonight, I checked on Big Boss, my wonder gecko, and was concerned because he hadn't been eating...in almost two weeks. I tried picking him up, and he squirmed a little but was otherwise compliant. This is highly unusual. He would normally be halfway to Timbukbu by the time by finger brushed up against his side. Anyway, I pick him up and start picking shed skin off his toes and legs that he hadn't gotten to yet. He was not putting up a fighting, just chillin'. So I get to his legs and notice that his vent (butt) has a kind of scabby thing stuck in it. That means he's impacted. So I sterilize my tweezers and try to pick it out. Again, he's not totally into it, but he's not going crazy, either. However, it's still hard work because Big Boss isn't having a great time. So I do what I used to do with Liquid--stick him in the fridge for a few minutes to cool him down.

So I do that. Big Boss comes out still sort of moving, but half asleep. I flip him on his back and get to work on the impaction. I actually manage to get a bit out, but it'll take more work. When he starts to wake back up, I give him a break and stick him back in his tank. Naturally, I start reading online about how to dissolve an impaction. Hey look--let him stand in a warm pool of water for about ten minutes. So I fill a shallow dish with warm water, get Big Boss out again, and put him in the water. Again, he's not struggling.

Then the trouble starts. While he was initially standing in the water, he quickly goes limp. The second his nose hits the water, I pull him out. This lizard is completely limp. No idea what just happened. The end of his tail is twitching, though. I put him back in his tank under the heat lamp and let him lay there. A few minutes later, I check back. He's changed positions from laying on his belly to a rather unnatural sideways tilt. I continue to watch, and then the freakiness happens: his body convulses uncontrollably--I can't tell if he's half-paralyzed or having a seizure. These convulsions are very short but occur once every few minutes. It becomes pretty obvious that his brain is not turned on right now. Eventually the convulsions stop and his body goes stiff. He's dead. I actually suspect he died in the bath, and the ensuing convulsions resulted from background electrical activity. Think about a lizard tail that's dropped--it flips around for up to an hour after it's separated from the body.

So here's my question: What the heck happened? And don't say metabolic bone disease (MBD) because he's a fat, active, healthy gecko aside from this impaction, which I suspect wasn't more than a week old. Any ideas? I'm sad, but I'm also just plain curious. I'm suspecting a heart attack or a stroke, but can lizards get heart attacks and strokes?