It all started on Monday. I drink a Pepsi, I get the shakes. I have the shakes for a short time.... then later I drank another and it happened again. When I get home, I chose to drink water. That night, I'm getting the shakes and my stomach shakes (feels as it does when you're really cold) but I was not cold. I then went to sleep only to wake up to the same feeling in the morning with side pains on both sides. As I got up and moved around it soon calmed down. The whole day my Muscles felt weak, at one point they didn't until my legs had a muscle spasm, then my legs felt weak again. I had called my Doctor about it and told him how I was feeling. He told me to take Pepcid AC and call him on Thursday and let him know how I'm doing. Well, That night, I have the stomach shakes again. Not as bad as the night before, but I still gained stomach pain after eating. I got up on that Wed. morning and did not feel as bad as the day before. The Muscle weakness is now gone. My Stomach only hurts every once in a while but mostly after I eat. The day goes as normal with few shakes. That night they come back as they have the last 2. Thurs. morning was not as bad as the day before it. I called my Doctor. I spoke the his secretary and told her how I was doing and she said that it sounds like too much caffeine is to blame and due to me not drinking it I may also have withdrawals from it. She told me one of her friends went through the same thing. Here it is Friday and My lower back is hurting with Spasms in my spine at times. I think a lot of this may be due to a bad mattress I need to replace.