For what you want to do an MPH or an MBA concentrating in healthcare management or perhaps an MPA in development would all be more useful than an MA in econ from any school. An MA in econ is usually an industry oriented MA in economic/econometric analysis. This might be useful if you want to use your MA together with your MD for research work in global health, but not for the more practical development and management stuff you describe yourself as being interested in. If you look at the econ forum we nearly always advise people interested in the practical side of development to go an MPA program over an econ program (whether MA or PhD).
A lot of med schools have a joint MD/MPH or MD/MBA program and you might want to look at those, though if you are not applying to med schools just yet this might not be practical for you. The NYU MPH in Global health would have been right up your alley but unfortunately, the deadline for fall matriculation has passed. There may be other programs in the NY area whose deadlines have not yet passed. CUNY SPH, Columbia SPH and Rutgers SPH all have very good MPH programs. Mt Sinai, NYMC and SUNY Downstate all have pretty good MPH programs. I don't know of any other decent ones in the NY metro area (Stony Brook is a bit far).
Most of the posts knocking the New School (a number of which were by me) were knocking the PhD program or using their MA as a stepping stone to an econ PhD. For that path the program is not good. For what you want, to use the MA as a terminal degree playing a secondary role to your primary terminal degree (MD) it would be fine, especially if you are partially funded, though as I mentioned above, I am not sure an MA econ is the best degree for what you want to do.