I don't know if this is the cause but your doctor is very right about taking it for only the 3 months. I was on it and I took it for a longer period. I originally lost 25lbs total and then I was at a standstill with it but it would keep me awake...not shaky but just not tired so after I was done losing the weight I found that I had to keep taking it...became addicted really because if I didn't take it I was a walking zombie, could sleep for 10-13 hours straight and would nap in between too. So be careful with it.