The 2nd day is the hardest for me physically. I'm starting my 3rd day today and I woke up feeling fine. Your body does seem to have given you quite a strong reaction, so you should see a professional about it. I've had headaches, stomach grumbling, felt lazy and a little weak, but nothing as strong as what you described. I don't think that would just be a mental challenge to overcome, but possibly a physical problem. I would consult a professional. I hope things work out for you. Remember, even if you just fast one day a week you'll see significant changes in your health.