Prickly skin

I am currently taking Nortriptyline 50 mg and have been on this dose since February, at the beginning I had a dry mouth but that has mostly went away. Recently I have been feeling what I can only describe as prickly feelings on my skin kind of like needles pricking mostly on my face, neck, arms and stomach. I don’t know if this has anything to do with the medication or is it something else. I also feel it more when I am doing something physical like ironing or hoovering or even walking. Just would like to know if anyone else experiences anything like this? Is it possible after 9 months I could be experiencing a new side effect?