Pain and swelling in the knee and ankle can be related to low calcium, which can weaken bones, and your body weight may also add extra pressure on the joints so that both factors can contribute to your symptoms. Low calcium can lead to bone and muscle discomfort, while excess weight increases strain on the knees and ankles. Focus on improving calcium and vitamin D levels, maintaining a healthy weight, and avoiding excess strain on your joints. It is important to follow your doctor's advice so that the underlying cause is treated and further joint problems are prevented.