They will to respond to the situation, and will move you to another location if necessary. That's not uncommon at all. In every country, there is a country director and staff that you would go to with complaints or concerns. Their job is to respond or resolve the situation. In the worst-case scenario, they will move you.
Every country has a medical unit and a medical provider.
If there is a health problem that occurs that can't be treated locally, then the volunteers are moved either to another country or back to the U.S. for treatment. I did the Peace Corps for two years and since I didn't want to continue teaching, I found it difficult to attain employment for some time when I came back to the States. Regarding the readjustment process, there's a close of service conference. Three months prior to the end of your service, there is a conference that all the volunteers attend that provides you with information on reacclimating yourself to the United States both personally and professionally. Also, they publish a bimonthly job bulletin and career manuals to help facilitate career planning and career options for returned volunteers.