Im no expert but I would have to guess the reason you feel the way you do is because of everything you listed above. Fasting's real purpose is not some crash diet, but it's to clean out your body. If you want to lose weight I think it would be better to completely do a real fast or exercise and watch what you eat. You have to understand that once you have finished fasting you have to make a complete change in the way you live and what you eat. If not then expect for all those pounds you lose to return, maybe more. Im not so sure how medication will effect you fasting, but I do remeber that when I was taking Ibuprofen for my pinched nerve it was recommended for me to have a snack or a small meal when taking the medicine if I felt dizzy or nauseous. So that could be the reason behind you feeling bad.