Doctor in the South End / Back Bay?

So, in my never-ending attempts to stop being a slacker and starting to get my life fully together, I need to find a doctor. I haven't seen a doctor in something like five years. I really would like to get a regular checkup, etc. Also, it would be nice if I had a doctor close by that I could go see if I am sick, like I have been the last few days. So, anyone have any suggestions for doctors in the South End/Back Bay area? Thanks!