Your mistake was to treat it like a real patient encounter. Passing this exam has little to do with your actual clinical skills, and almost nothing to do with your diagnostic acumen.
Agree with the above poster. Figure out what they're looking for and do it. I guarantee you it's something ridiculous, that YOU aren't doing because YOU don't need to in order to figure out the problem. But, again, the test is not about your diagnostic skills, it's about getting the SP to check off boxes.
Keep this in mind on your retake: the SP can't see your note, and can't give you credit for getting the right answer with a few key clues. He or she can only give you credit if you do what it "should" require to get the answer.
Likewise, the MD who sees your note can't see any part of the actual patient encounter. So the note needs to stand alone and support your conclusions, document what you discussed, your findings, plan, etc.
🙄 you've gotten past every other obstacle, you'll get past this one.
One last piece of advice: take the test in a different location next time. I don't know if it matters, but it can't hurt.