Get a job. Yes, it's harder to do in this economy, but the last thing you want to do is to go back to school right now (as you may or should've learned from your med school experience, going to school doesn't solve your problems for what you want to do - it only tells you what you do NOT want to do).
Even a lab tech job to hold you over can help.
Don't think about b-school or any school right now. Again, school isn't a magic slipper to solve whatever uncertainty or indecision you may have about your life/career going forward.
Doesn't matter what job it is. It's not only a rite of passage into adulthood (and yes, in my view you are not a *real* adult until you have had to work for a living full-time), but a way for you to root yourself in the real world and discover more about who you are and what you're truly interested in. You can't do that in school - school is a bubble - you're in a protected environment conjecturing about what the "outside world" is really like, oftentimes with students and professors who themselves have limited exposure outside a campus environment.
You'll have to get imaginative. Keep in mind that a lot of people don't end up working in careers that have anything to do with their undergrad degrees.
Engineers working in hedge funds or consulting firms.
Biochem majors working at an ad agencies.
English majors working as assistant brand managers at consumer products companies.
And so forth. Especially in business, you don't need a business degree -- you need hustle more than anything else.
You gotta find a way to get a full-time job. That first job is probably not going to be ideal, but it gets you working, and from there you can grow and begin to find your place in the working world. And even if you do jump around a bit from one job to the next, it still beats going back to do yet another masters at this point especially if you don't know what you want.