I'm not really educated on this subject (read: not an adcom) but to my layman's perspective I think you're overreacting
You have one bad grade and the rest C's? I think you're going to be fine. Continue your study habits with the MCAT, do well on it, and keep your pace (A/A-) on Heme, A&P, Orgo and Phys and in my opinion you're a shoo-in.
Like I said though, take what I say with a grain of salt. Consult with one of the adcoms on here.