Yeah, sounds like me. I had calculus in HS and took Honors calculus at UGA as a freshman. We covered all I knew about calculus in one day at the beginning of each quarter and then were off to the races. There were about 18 kids in that class and I figured I was one of the dumbest. It was humbling. I vaguely remember something about Green's theorem. The professor wrote on the board with one hand and then erased what he wrote. Nothing related to the text book, at all.
I placed out of the first quarter of honors chem, and that was a mistake. I ended up later making a D in the third quarter, and decided to change my major to computer programming. I was too lazy to do it. So, next up was org chem, which for some reason was right down my alley, due in large part to Professor M. Gary Newton, who was one of the best teachers I ever had. The class started with 180 students, many sitting in the aisles, and ended with 33 by end of the year, most headed to medical school.
Humbling is good. I was arrogant and didn't know how to study. Looking back it was a miracle I managed to get through it all.