I agree with swaffles...it's too late in the game to retake the GRE. I also don't feel your GRE scores are particularly bad or will restrict you in any way from gaining admission.
Ideally you should have submitted your applications earlier to give yourself the best chance for funding, but I still think you have a chance at receiving funding from some schools.
In the instance that you gain admittance to schools, but do not receive any funding...are you prepared to reapply (early) next cycle, or will you still attend this fall?
-waystinthyme
I agree with what has been said. Unless your main goal is to retake the GRE to use this (potentially...albeit uncertainly) 'better' score in your future endeavors, and do not want to deal w/ the god-awful new version of the exam that will come out in August, then I would agree w/ your reasoning; and would advise you to study a few months for it prior to retaking....since time constraints are things you typically can't work-out in a matter of a week....I mean...unless you are good at timed exams to begin w/ and you simply had a bad experience on test day the first time around. Otherwise, you're GRE score is only ONE part of your app which will be equally considered to your purportedly excellent RECs, extensive experience, and a panoply of honors--in combination w/ a decent GPA (not the best GPA in the universe, but perfectly acceptable for most competitive MPH /PhD programs).
I'm also pretty certain that by the time your new GRE scores, not only reach the schools, but also reach SOPHAS-- by the time they are validated, uploaded, sent, and compiled w/ your original application, most of your schools will have already reviewed your app, probably won't see your scores, probably won't even consider them as part of their eval for funding...and frankly you probably aren't certain how they will use your re-take GRE scores in the first place. Do they average them out? Do they take your best sections? Do they consider only your most recent scores? You won't really know. And, if you achieve only a modicum of improvement, in such a case, your GRE score probably will do little to affect their decision in the first place.
My advice: Send a 'Get-Well' card to your REF, open up a good bottle of brew, down the hatch, and just chilllllll. You'll be good to go. Also, unless you live in the boonies, finding a test-taking center w/ available seats will be difficult in a weeks time. I think they advise people to register no later than a month prior to your intended exam date. So, good luck w/ this if you find a testing center that can accommodate you in a weeks time. If I was in your shoes, I wouldn't be able to pull off such a feat, given where I live.
Good luck!