Your ability to get into medical school will be based on a lot more than a single class you got a C in. Things that will matter are how you did in all of your other classes, what math class it was that you got the C in, whether you have a reasonable explanation for why you got a C - it might even be reasonable to say "I'm not really a math person" - if you got A's in your other classes. If you got C's in biology and math, it probably won't fly to say "I'm not a math or biology person".

What math class is it, by the way, and do you need to take the next class in the series? Also, do you feel you did poorly because of something that you can change - either a bad teacher or being too distracted during that semester? Or is it that the material is just too hard to understand? If it is something you can change, then you'll need to change those things when you take your next math class. If it is that the material is too hard - then you'll probably continue to struggle and perhaps need to accept that a C is what you'll get in your math classes.