We are all subject to self doubt, momentary or otherwise. Unfortunately, it is a common human condition.
Some let it bring them down needlessly. While others learn to cope with, work through or around it.
One of the benefits of life experience is that we learn, through trial and error, that, 9 times out of 10, feelings of self doubt, anxiety or fear, fall short in reality. In fact, we usually end up just fine.
Think positively, search for lifelines and Silver Linings. Look at the bright side.
We can all be winners!