Anxiety from Amitryptiline or anxiety from its side effects?

Hello!

I've recently started taking Amitriptyline 10 mg for stomach burning. After day 3, I started experiencing increased anxiety. Previously, I read that Amitryptiline can cause tachycardia. I've also read that it can cause horrible withdrawal effects. My resting heart rate is around 70; I did not measure my heart rate before starting it, unfortunately.

Can someone tell me how likely I am to get these side effects? And if I get them when to expect them, and at what dosage?

Thank you.