We propose an auxiliary relief mechanism (ARM) for a wireless body area network (WBAN). The ARM, as a supplement to the traditional medical assistance provided by a WBAN, aims at solving the problem of the lack of timely relief in the existing WBAN relief mechanism. When an emergency occurs, it can help RSs find k potential rescuers (PRs) nearby. By fully considering the limited energy consumption and dynamic characteristic of auxiliary relief network (ARN) nodes, we propose an ARN dynamic population clustering algorithm for the ARM to cluster people around RSs, which uses dynamic uneven clustering to ensure balanced energy consumption between clusters. On the basis of the clustering, a rescue request information (RRI) diffusion strategy is proposed, and appropriate intracluster and intercluster propagation strategies are adopted to spread the RRI, so that the information can be transmitted quickly to k PRs. Our experiment shows that the ARN dynamic population clustering algorithm realizes uneven clustering for a dynamic population. The ARM RRI diffusion strategy is superior to a comparative algorithm in both searching time and energy consumption, and has higher searching efficiency.