Well I think if your final goal is academic and you need a PhD degree anyway, maybe getting another MPH/MS is not as helpful as working as an RA this year and applying for PhD program next cycle. Especially if the tuition fee could be a burden, working as an RA can get some salary and also make you concentrate on research and publications.
But also don't give up this early! As long as it's not 4.15, all waitlists and no responses still have a great chance!