For me,much of my self criticism comes from all the things I was taught,told and believed about myself in childhood that repeats in my mind.

Yes,I believe it's something that can be changed with alot of work.I started a journal just to work on that kind of stuff.I wrote down each believe and then challenged them.For example believing that I am worthless,I wrote about why I was called that in chiodhood,how it made me feel,how I believed it,etc.Then I wrote about how I wasn't worthless,I was just a child,there was something wrong with my parents that made them make me feel and believe I was worthless,it wasn't true.

What helped me more than anything was/is comparing myself to any other random child and knowing no child is worthless,useless,stupid,etc.and knowing I am NOT all the things I have believed.It's hard to change all that old stuff that replays in my mind but it has got much better with challenging them.

I don't know when or where or why you learned all your self criticism,but knowing is a good place to start.