Yes and no. I'm in a similar position, but for me the MPH is something that I would have done anyway - the timing is all that changed for me. I'm also still very much on the fence between MD and research (either microbio or epi as a PhD), and the MPH is useful for both. If you don't have an interest in public health, the MPH won't help - there are other and better degree options (such as the SMP) that are also cheaper. The MPH might help a little bit (if you and another candidate have the same stats and they need to pick one, your MPH will stand out), but since it's not seen as a science heavy degree (even epi, which is frankly ridiculous) the GPA is expected to be high and can't compensate for any low ugrad GPA. If your goals are, as stated: "I want to travel to other countries, help those in need, experience different cultures, and exercise my leadership qualities in international healthcare as a physician", then the international health MPH is not for you - I'd look into the peace corps. I'll be enrolling in an international health program this fall, and while I have to complete an internship abroad (in a developing country) it will be more focused on research and study implementation than directly helping people through volunteer work.
One other thing to keep in mind is that public health is a wide field - you have everything from statistics (biostats and epi) to social sciences (health behavior), with hospital administration thrown in for good measure. I'm not sure what you mean by "International Health" - this can be a subset of any one of those fields.
On the plus side, I can't imagine that the MPH would hurt (as long as you don't do poorly). Just don't expect it to be a make or break issue.
