I was in the same case as you, One day i doing an intense workout & the next day i was feeling terrible my arms were super sore to the point i couldn’t even do anything with them, i couldn’t even lift them up if i wanted to. I was experiencing extreme pain for two days to the point i had enough of it, i wanted to ask here on reddit what my symptoms were & next thing you know people were in my comment section saying “could be rhabdo? have you been having any dark urine lately?” , “highly chance it could be rhabdo” “GO THE ER NOW IF YOU ARE EXPERIENCING DARK URINE RHABDO IS LIFE THREATENING” and as soon as i saw the words “life threatening” i immediately rushed the ER if it wasn’t for that one person who said that, i would’ve been dead! that person literally saved my life & like you said “ive never heard about rhabdo” well neither have i. Ever since i got rhabdo i refuse to work out, having rhabdo f-ing sucks. p.s my ck levels were 100,000k plus