I don't think the vitamin D has anything to do with it, read this >>>>> Vitamins and minerals - Vitamin D - NHS Choices

It does sound like there is a mental health issue going here, depression and anxiety can cause the feelings that you express here but we can't diagnose on this site. You could try these online tests to get more of an idea of what is going on with you and then share it with your doctor >>>> The Sanity Score - Test Your Mental Wellness and Psychological Tests and Quizzes