Amitriptyline side effects

I have been taking Citalopram 20mg in the morning for some years to help with anxiety and they help a lot, but recently I have also been prescribed Amitriptyline 10mg taken at night to help with my lower stomach pain.

I decided to stop the citalopram a couple of days ago just incase it was not a good idea to be on two different ant-depressants.

The Amitriptyline do seem to be helping, but today for the first time I woke up and feel very agitated, just wonder if it could be caused by this medication and if so, what should I do.

Any thoughts please.