I have been on Generic prozac 20 mg for 13 years. I retired 2 1/2 years ago. In the spring for the last 2 years i notice i have more anxiety, mainly shaky feeling more in the morning. By mid day i do not notice it hardly at all. This feeling usually goes away by end of summer. My Primary Dr. Suggested taking 40 mg. I was not sure if that was too much, started taking 30mg every morning for the last couple of weeks. The shaky feeling is really good some days and others not so good. I was looking for suggestions to help with this feeling. I eat right, get plenty of sleep and exercise daily. Can the original medication dose stop working after years?