Drowning.

After spending some time with Song and TiHao, he returns to Kori's home and heads to his bedroom, to take a nap. He counted to sleep a couple of hours and wake up with a less painful headache, so that he would be able to take care of ShiHao's matter that same evening. He even told to TiHao that he'd do it that in some hours, since he was very positive that he'd get better after resting.

The nap, though, lasts much longer than he had calculated. He sleeps the whole rest of the afternoon and all night, waking up only the next morning.
All of his memories are back and they mix up with all the new ones he made while living with amnesia. Now he really is back to his usual self and he remembers everything that happened while he wasn't in his right mind too.

What he feels, beyond anything else, is a sense to absolute terror. It's so intense it triggers a very strong panic attack, the worst he has had in his whole life, despite he always suffered from panic disorder.

He phones YiXing, since he is the first person coming to his mind. He thinks Kori might be busy with work and wouldn't be able to answer it. "Dowajuseyo, dowajuseyo, jebal!!"

(...) When YiXing shuts the call, he feels even more scared and starts to send the same vocal message to all the WhatsApp groups he is into.
"Dowajuseyo, dowajuseyo, jebal!!" he sobs loudly while crying desperately, even in the message.