Hey, I'm sorry to hear about your midterm. This was orgo II, and I ended up scraping out a B-. I was actually pretty proud of that B-, since the way our professor graded the class was to set the class average as a B- and scale up/down from there. I did
not withdraw (no way in hell was I doing orgo all over again, and like I said, proudest B- I've ever gotten). It was several years ago at this point so I don't really remember exactly what scores I got on the rest of my assignments, but I think my final percentage ended up being around an 84%. One of the big saviors of my grade was the lab component of the class - If you have a lab grade averaged into your course grade, that is something that is easy to focus on and do well in even if you're struggling with tests. Homework can also be really helpful, not only in padding your grade a bit but also in working through tough concepts, so don't half-ass that. 66% is a lot of grades left, and a lot of chances to pull your score back up. Otherwise: show up to class, talk to your professor (cry in their office if you need to), maybe seek help from friends/other resources. I will admit that I was stubborn and didn't utilize some of the tutoring resources that we had on campus, but I'll be a hypocrite now and encourage you to do so.
I also suggest looking outside the class itself and seeing if there is anything else in your life that contributed to the bad test. For me, that semester was
really rough, for a number of reasons. I was overcommitted to activities, struggling with some anxiety/social issues, and taking upper div classes for the first time. All of that put me in a bad place and made it tougher to do well in the class. One of the big things I did after that semester was reassess my priorities, including quitting my sport so I could have time to focus on other things. It didn't do anything to fix my orgo grade, but it did set me up to do better for my remaining years.
Finally, a reminder: You can get into med school with a few bad grades!! You can do well on the MCAT even if you fail an orgo test! It sucks when its happening to you, especially when you see all kinds of perfect stats on SDN, but remember that a bombed test does not define your worth or your abilities. Hopefully this was helpful, and best of luck