For most undergraduate degrees pursued by pre-meds calculus is required.
(I ended up having to take Calc 1 and Calc 2, I thought Calc 2 was easier it was all just the reverse of calc 1... but i digress).
I thought quite a few schools required calculus, but I couldn't tell you any off hand.
Calculus is what you make of it. You have to put the time in to succeed, you have to do your homework and you have to practice.
I think if calculus is so utterly impossible, then maybe you might find medical school equally impossible...
I guess i'm trying to say its a challenge but its do-able.