Hi Cool, Have you cut back your caffeine intake? If you haven't try cutting it back a little at a time and increase your water. I find it helpful to make my water cold with ice and then add a couple of drops of lemon juice to it from a store bought lemon juice concentrate. This makes the water refreshing (not lemonade) and will also make you thirsty to encourage more water intake.
Also, where are you getting your protein? Try adding more beans to your diet. Here is a simple recipe :
Confetti Beans
1 onion, chopped ; 2 bell peppers chopped (I like 1 yellow and 1 red for color); 1-2 cloves garlic pressed (you can add a couple tablespoons of jar garlic already minced to make it easy); 1/4 C water; 1 can red beans, drained, 1 can pinto beans, drained, 1 can black or garbanzo beans drained; 2 C frozen corn; 1 15oz can Italian or Mexican stewed tomatoes, 1 Tb. Chili powder; Black pepper to taste.
Saute the onion, bell peppers and garlic until softened. Add remaining ingredients cover and cook on low heat for about 5-10 min.
You can eat this just like this or over a plain baked potato. My kids love it and it is very filling. Your body will get the protein and sugars it needs from the beans. I think you will find if you try to get your protein this way 2-3 times a week you will see your energy come back. In the past when I have gone Vegan I found if I did not eat enough legumes during the week I would feel just like you described.
Hope you feel better.
Theresa