Vitamin D plays very important roles in human body. Its deficiency can be due to inadequate sunlight exposure and inadequate intake. Liver and kidney problems can hamper the absorption of vitamin D in body. Symptoms of vitamin D deficiency are bones pain, frequent fractures, bone deformities etc, So, feeling tired is not directly related with Vitamin D deficiency. Tiredness is condition which can be due to thousands of reasons. In my opinion, you should visit your problem with physician not with GP.
