You need calculus for medical school. You'll need it for calculus-based physics. You're both in luck as calculus is what I taught in college.
I tried calculus in high school and did kind of meh. I tested into an accelerated/honors Calc I and II+ in college and it really, really clicked. From there, I took all honors math and earned a minor. It really just takes a slightly new way of thinking. Once you can get there, you can work a problem and you'll KNOW if the answer is right or not just by looking at it.
I honestly believe ANYONE can learn to think mathematically. You just need decent instruction.
Fun story: one of my students was a jerk who picked on me and my friends in high school. In college, dude kissed my ass hard, which was sweet revenge. He was dumb as a brick, but I saw him after our class ended one day and he ran up and hugged me and said, "Bagels! Bagels! I passed! Thank you so much!!!" His mom made me fucking cookies. :/ I was pretty proud of that, actually.
(My brother is finishing his math PhD, so if we need to call in the big guns, we can do that, too.)
I'll dig up my old med school thread. We can talk more about that, too. It's a tough course of study, but nowhere near as hard as some people think.
Jubei - people on here obviously like you. Seriously, if you weren't across the country we'd go hang out. You sell yourself way short.