I am a neurologist. And I went to Northwestern for both undergrad and medical school. You seem a little lost so I'll give you some background on the process.
You will apply for college next year. NU is hard to get into, but it sounds like you're local so that will help you. In college at NU there is a very large pre-med population, and the first 2 years of chemistry (inorg and org) and biology are essentially weed-out classes. They are hard. You can major in anything you want, but you need to take the standard premed requirements, which include math, bio, chem, physics classes that are both prerequisites for medical school as well as needed prep for the MCAT. The MCAT is like the SAT and ACT for people who want to go to med school. You will take it in your junior year of college usually. Then you will apply to medical school, and if you are both smart and somewhat lucky, you will get in.
Medical school takes 4 years. The first 2 years of medical school are pre-clinical, meaning you take more classes, like college in a way but much more intense with respect to the information load. These classes teach you anatomy, physiology, and pathophysiology. After the first two years of medical school, you take the USMLE, which is like the MCAT for medical students who want to get into a good residency. While strictly all you need to do is pass, the better you do, the more likely you are to get into high-demand residencies like dermatology, radiology, ophthalmology, and other competitive residencies like orthopedic surgery.
After the first 2 years of medical school, you enter the clinical years, where you go into the hospital and take care of patients (sort of). You actually are a sort-of low level assistant that gets in the way a lot and tries to learn how to examine patients, perform history and physicals, how to operate, etc. During clinical years you will get enough exposure to each specialty in medicine to pick what kind of doctor you want to be.
In the 4th year of medical school, you then apply to residency in the field of your choice. There is a complicated application and matching process that occurs, and upon graduation from medical school you report at the hospital you matched at for residency. This is when you learn how to be a real doctor.
The first year of residency is called internship. You take care of patients and have the power to write orders, make decisions, and potentially do a lot of damage. Fortunately, you are supervised by both senior residents and attendings (doctors who have completed residency). Internships can be medical, surgical, or tailored to specific specialties. For instance, OB/GYN interns don't do a strictly internal medicine or surgical internship, but rather one tailored to the needs of their specialty.
After internship, you enter residency proper. Residencies last from 2 years (internal or family medicine, one medical intern year plus two additional residency years) up to 6 years (neurosurgery, one surgical internship plus 6 additional residency years). Some residencies have research years built in, which is why specialties like neurosurgery are so long.
During residency you make a very meager salary, and you are worked like a dog. Residency work hour rules are changing, but in my residency years I worked 80 hours a week much of the time, with shifts lasting 12-30 hours. Being "on-call" means that you come to work in the morning, work all day, then cover for everyone else all night when they go home, then work all morning the next day, then go home around 1pm. You typically do not sleep during this period, because the hospital is short-staffed and there is no one else to do the work if you are sleeping. You will then work the next day as usual. Call schedules are cyclical, so when someone says they are on q4 call, they take call every fourth night. And yes, weekends count.
After residency, you can choose to either become an attending physician and start practicing independently, or you can enter a post-residency fellowship. Fellowships provide research and clinical time on top of residency to obtain additional subspecialty experience.
I did 4 years of college, 4 years of medical school, 1 year of medical internship, 3 more years of neurology residency, 1 year of research fellowship, and am now doing 2 years of neurocritical care fellowship. I am currently in my sixth year of post-graduate education (PGY-6, counting since medical school graduation), with around $300,000 in educational debt (thanks, NU!), and since I'm still a fellow I make around $62,000 a year. Because my fellowship is not strictly held to work-hour regulations, I still work around 100 hours per week in the hospital.
Medicine is a very unique career path, but it is not easy. It also doesn't get a lot easier as you advance. You will make decent money once you're out of residency in most cases, but you're probably not going to be buying a yacht any time soon. Taking care of patients is an amazing privilege, and it is rewarding, but it gets very difficult to remember that at 4 in the morning when you get your 8th admission of the night and you haven't eaten since breakfast the day before and you're filling out the paperwork to forbear your loans for yet another year.
Would I do it again? Probably, but I would have done more research early in the process to understand what I was getting myself into. As an ICU doctor, it is nice for me to go home and know that I accomplished something significant each day, like keep someone alive who otherwise would have died. You can't do that as an accountant, as far as I know.
