Don't quit man. Biggest mistake you would ever make is to quit. I hear you though, it's super tough. You're under acute stress now, wait and let it pass and get back to drawing board. I don't know your step1 score, but I've heard stories, personally know people who failed Step 2, didn't do well on step 1 and still found residency. The only thing that is under your control is a hard work, and persistence. If in 1940s people quit after first defeats most of the Europe would be speaking German now

What about studying for CK now - while you're still fresh? I think you can improve the most now vs later, when information would fade.

You can reschedule things. There's a software called check4change. You can read about it in forums, it was very useful for me. I was able to catch openings that lasted only a minute and reschedule. CS is a completely different test, esp after CK.