Ok, so is your goal PA school or med school - your wording was a little off there ("applying to medical school"). Are you currently in an MPH program? If not, I don't know if completing an MPH would be a good use of your time. Most MPH's take at least a year to complete - more if you're going part time, which I would assume you are since you mention working full-time. Do you have the clinical hours necessary to apply? I would focus on taking only the courses you need for PA school, and boost up your clinical hours. There are dual PA/MPH programs that you can apply to if you'd like, or you can get your MPH after PA school. But if PA is your goal, I wouldn't do MPH - save money and time and get it later if you really want.