Hi,
I too suggest you to avoid caffeine as it may cause some dangerous effects. And being a vegetarian you should be careful in your health because you wont get all needed nutrients from veg foods that you have written that you have been cutting backed on sugar, cheese and eggs for past one month which clears that you have no taken any protein rich food. so if you want follow the same in future better some natural nutritional supplements which helps you to maintain the over all health and good energy level.
Thanks. Yes, I do all the "right" vegetarian things and I actually just got my B12 checked due to some peripheral neuropathy I've been experiencing (B12 levels came back fine and my iron is actually high). I guess I'll just chalk up the headaches to caffeine withdrawal, though I still have two cups a day (down from 4 to 6) and the nausea to the headache.
Usually when people lower or avoid caffeine after drinking large amounts daily, they experience headaches and some nausea. You stated that you have cut back on cheese and egg. Have you added additional protein sources to your diet with decreasing eggs and cheese? They are protein sources and you need protein replacement. As a vegan you need to combine grains and nuts / seeds for essential protein have to be used daily such as rice and beans, pasta and beans, nuts to oatmeal, peanut butter and bread, and salad and nuts. You can also eat the soy milk and rice milk, too. Vitamin B12 needs to be supplemented if you are a vegan vegetarian. Blood work can reflect low Iron stores when Vitamin B12 is deficient. Suggest getting your Vitamin B12 levels checked. Good sources of information on vegetarian eating are the American Dietetic Association website, www.eatright.org and Vegetarian Resource Group website, www.vrg.org. Hoped that helped you.