Why Do I Feel Bad On My Vegan Diet?

I started at temporary vegan diet about a week ago and about 3-4 days into it I started to feel really tired and have been getting headaches. I know that I am not properly stocked up on the foods I should have to get proteins and carbs so what types of things should I buy for my diet?Why Do I Feel Bad On My Vegan Diet?
You are probably feeling tired because your body is not receiving the nutrients that it needs (possibly protein or iron), or you may be deficient in calories. Great sources of protein while following a vegan diet include cereal and food grains, nuts and seeds, legumes (kidney beans, lentils, chickpeas, split peas, etc.), seitan, tempeh, tofu, vegetables (peas, corn, collard greens, mustard greens, turnip greens, broccoli, etc.), and fruits.