Which of the following statements made by a patient's family member would lead you to suspect that the patient is suffering from hypovolemic shock?

The statement made by the patient's family member that indicates the patient is suffering from hypovolemic shock is that he cannot stop throwing up. Hypovolemic shock occurs when the body experiences a significant loss of blood volume, which can result from various causes, including severe dehydration or significant fluid loss due to vomiting. In this context, persistent vomiting is a critical sign as it can lead to further fluid loss, exacerbating the patient's condition and potentially leading to decreased blood volume, poor tissue perfusion, and shock.

The other statements indicate symptoms that could arise from a variety of conditions but do not specifically point to hypovolemic shock. Extreme fatigue can be a result of many factors, including psychological stress or underlying illness, but it is not a direct indicator of fluid loss. Headaches can arise from dehydration, tension, or other medical issues without confirming hypovolemic shock. Similarly, joint pain may relate to musculoskeletal or inflammatory conditions and lacks a direct correlation to the volume of blood or fluid status in the body. Thus, persistent vomiting stands out as a symptom particularly linked to the potential development of hypovolemic shock.