The Peace Corps is the agency that pays your medical bills directly while you are in the field, during medical evacuation, and upon your initial return to the US. Then your medical bills are processed by the US Department of Labor where you will be passed off to a federal Claims Examiner. Those bills and any disability payments still come from the Peace Corps' budget.
The Executive Branch of the US Government administers the following agencies that you will be dealing with. Here’s a summary:
USDOL: The US Department of Labor determines whether you can get medical care for your health issues after you have completed Peace Corps service. They have Claims Examiners (CEs) that review cases. The CEs are not part of the Peace Corps.
ACS: Affiliated Computer Services manages the payment of bills for the USDOL.
FECA/OWCP (Federal Employees Compensation Act / Office of Workers’ Compensation Programs) is the part of the USDOL that determines if you are eligible to receive Loss of Wage Earnings Compensation (disability).
US Treasury Department is the federal agency that processes the medical bill reimbursement or loss of wage checks for you.