Definitely drink milk if it agrees with you! It tastes delish and is high in many valuable nutrients. Unfortunately, it does not agree with everyone, for one reason or another.
I was a biochem major, which really helped give me the background to better do my own research and understand scientific literature on my own. No class I ever took (undergrad or med school) taught me anything particularly practical, but I can’t say that is was completely unhelpful. I think the hardest thing, and the thing to be most careful about, is to be critical with the textbook stuff taught in schools, on encyclopedias, and disseminated through ‘popular’ culture/doctors/television. I may be wrong, but I have come through my own investigation to disagree with the vast majority of stuff considered ‘fact’ by the authorities. I think that’s the same for Matt Stone and others.
I do recommend that you take the premed courses that you need, but also don’t shy away from other courses that you just WANT to take. I regret not taking more history and language courses, for instance. You may never get the chance to take some of these again. So have fun!
I wish you the best of luck in your studies! We’re all students! As a look ahead, you may find as you move forward with formal education that teachers and the ‘system’ are increasingly hard on free thinkers, and that just regurgitating what the system wants is easier for you than swimming upstream all the time. Following orders would not be so bad in this case. But do please keep an open mind and, at least to yourself in your own head, be critical of what is being taught. I don’t think there is a stronger propaganda program in existence than what is fed premeds and med students in our country.