I took calculus 3 a while back and received a D+ in it. I got a B- in calc 1 and 2. I'm not sure if I should retake it because, I honestly don't remember anything from calc 1 and 2 anymore, so I'm pretty sure I would do bad again. Also, the medical schools I want to apply to don't have a requirement for calc 3. The only reason I took it was because i was majoring in computer science before but then later changed my plans. It does bring my gpa down alot though.