Also, at some level you'll probably want to think about what would happen if you ended up not going to medical school and want you would want to do. I first was in our bio program and after a year switched out after i realized that there was nothing I would want to do with that degree if for some reason I didn't go to med school.
Yeah U of Pittsburgh isn't the only school of course, its just my #1 as of nowAlright dude, before I give you advice you need to take three deep breaths. Seriously, do it.
OK, now that is done I'll give you advice. It's good that you have drive and a particular goal in mind, but you shouldn't have tunnel vision. UPitt is a few years away, and you may change your mind on your speciality after your rotations. A good doctor is flexible and adaptive, especially in the mental health profession. Your next few years are going to be a heck of a lot smoother if you roll with the punches rather than having a rigid agenda.
The major you pick should have two aspects to it: 1) you are truly interested in it, and 2) it is a good long term investment. While only you can decide which major is best for you, I would personally go with the science major with a liberal arts minor. If you find out that medical school is not what you want to do, a science degree may go farther in the working world than a degree in history; especially with our current economic state.