**I am not a doctor, and this should not be construed as medical advice.**
Rhabdo is too serious to mess around with. If you suspect you have it, you need to see a doctor ASAP, IMO. Also, dark urine is not required to be diagnosed with rhabdo. In fact, one of my Marines was diagnosed with rhabdo a month ago without the "classic" coke-a-cola urine symptom. (This is why I know more about this than I care too!). Also, like a heat injury, once you had rhabdo once, your are more susceptible to coming down with it again.
The interesting thing about your story is that usually rhabdo is associated with new unaccustomed/unconditioned workload. In my Marine's case, he did a AMRAP-style WOD, followed by a 20k hike in the heat (don't ask me why!) If you've been doing this routine for years, I wounder what changed in the last month to trigger overexertion?