For so long I was getting tons of caffeine through soda. Then recently, I took an EC stack for 4 months. 400mg dosing of caffeine at first, and then 600 for 3 weeks or so near the end. After stopping, I feel real lethargic sometimes throughout the day regardless of my food intake (really high and good) and sleep (good most of the time). Is it from the caffeine withdrawal? Will this feeling go away soon? Or should I just take 200 mg before working out?