Answer:
Pain in her lower back
Step-by-step explanation:
While the other symptoms are important to take into consideration, when diagnosing a patient, pain in the lower back is either related to muscle pain, or kidney infection.
Headaches behind her eyes can just be a result of stress, or lack of sleep.
Stomach cramps can be related to indigestion, and might also be caused by the kidney infection (not necessarily relating to the stomach, just that general area).
Dry skin on her arms and legs might be due to stress, but there is very little chance kidney disease is to blame. Unless it is to reduce sweating because the kidneys are not producing urine.