In 2 days time, the only thing you could have done has to do with water quality and acclimation, .2 ammonia is concerning because it should always be 0. During acclimation, sg must be matched, if your tank sg is .002 or higher different, there's needs to be an extended acclimation to bring this up before introduction. Much to common knowledge you must equalize sg and ph, going to a lower sg in your tank is of no consequence. You can't do anythiong about the acclimation, but the ammonia needs to be zero.
Things that go wrong with lions that is of no fault of yours. If what you are describing is like a seizure, being caught with cyanide is a likely cause, and there is nothing you can do, and he likely won't make it. If his color fades during this episode then it is more likely that it was cyanide. If he had been kept in a copper system or exposed to meds like copper or antibiotics, the stress of the move could trigger an internal organ hemorrhage, which again there is nothing you can do, and he likely won't make it. Internal parasites usually don't show this way unless in a very advanced stage, at which point you would almost certainly see white stringy poo hanging, and he would usually have a sunken belly.
I can't see the vid.