Mate, ANY player whos not a VERY experienced player will experience this occasionally. Its just the way it is but youve just gota get it out of your head. You know the cards are random and not out to get you so just forget about it and play your game
The lack of confidence is always linked to a losing run and repeated beatings which WILL happen inevitably if you play a lot, theres just no eascaping it. I know EXACTLY how you feel. Almost a feeling of impending dread everytime you pick up AA or KK
Just play your game and continue being aggressive, results WILL turn round and even perhaps after 1 very good game youll feel totally unbeatable again.