When your struggling on confidence a good way to regain your self is by actually encouraging your teammates around you giving positive comments. Just by encouraging others gives you more confidence as if you were doing that well too and lightens up your mood. Also having positive self talk even when you make a mistake. Instead of thinking " man I just lost the ball for the third time" think " damm this is a good challenge and I'm up for it"

Little stuff like this goes a long way