I'm so confused.. 💀 Could someone break it down for me ?

Confused about what?
The professor seems to be in rut so he was probably waiting for an omega (hence why his secretary thought MC came for Mr Cha)
The drugs are having huge side effects on MC with amnesia, hallucinations and paranoia (jiheon was probably not there in the rain).
We know that smtg happened to MC when he was a kid (aka the dream) and that Jiheon feels guilty about smtg (but we don't why yet).
(づ￣ ³￣)づ Here is what I remember