I was on 20 mg of citalopram for 9 weeks, starting getting bad headaches for 2 weeks and anxious. Per doctor, tapered down to 10 mg for 4 days and then stopped and switched to 20 mg of Prozac. Last few days have been horrible. Headaches, anxious, tight chest, twinges in left arm and chest. Is this caused by the switch in meds? Don't want to take my Prozac tonight